Are you going to sit on it for awhile then flip it? If not, you're overthinking it in my opinion.
If I rebuild the seats and interior is that ok, or do I find other seats and keep mine on the side.
Either way. The stock ones are cool, but new seats will be more comfortable for sure. The ripped up originals have maybe a tiny bit more retro-cool factor. But only a tiny amount. Extra value? I doubt it in the current market.
Whatever you do though, don't molest, or bring any harm to the floor mat.
At this time it's an irreplaceable part. Individual floor mats to protect it from your heels would be a good addition.
The engine will need to be rebuilt because it is original and not set up to Non lead gas. I'm sure it's eating the valves although it does run very well.
Well then it's not original any more and removes much of the potential survivor value of the other original parts that are still capable of being used.
And makes the thoughts of not even cleaning the underside or buffing out the paint pointless.
You could pull the engine as-is and save it, put a new one in and enjoy that one. That would give you the best of both worlds in fact.
Instead of that though, leave it alone and use the lead additive for the gas.
Some are ridiculously expensive, at a full bottle per tank. But there is one that is a multi-use dispensing bottle (Sta-Lube maybe?) that will last a long time even if you drive it daily.
That's what I used on mine until I finally had a valve job done (never did rebuild the engine other than the heads and it still ran great at 175k miles).
What makes you think yours needs that much work? Maybe it's just tired of sitting and will clean up nice with driving and some cleaning. Or is there something you already know about that needs replacement parts rather than just a little TLC?
There is a lot of dirt and surface rust on the underneath axles etc along with the brake lines. Can I change that out too as a safety prevention along with power disc brakes and power steering, although it may not need the power steering.
Again, are you flipping it or driving it? If you're going to drive it, there is no question that I would at least inspect the lines in some way, rebuild or replace the master cylinder, and replace any worn steering components.
If you don't see a lot of rust along the brake lines though, I would leave them and just flush the system for now. But do still check them extra close.
Dirt and faded metal don't harm the inside. But moisture inside does.
Change the fluid for sure. In the interest of keeping some things original when you can, you could rebuild the master cylinder rather than buy a new one.
What size tires? Presumably still the small ones, so you don't necessarily need power brakes any more than you need power steering. You just need all the regular bits to work to the best of their ability.
If there is any doubt, it's safety you're working on here. Not future value, so things like that get replaced for sure. Value be screwed, or consider that the enjoyment and safety factor
ARE the value.
My aim is to make it safe to drive with very minor mod's to it. I'm sure getting the paint buffed out is ok too, is it. Would this win any cars shows as it is since it is a true survivor. When does it become a non survivor. Ie seat covers etc.
You just answered all your own questions with that statement. You're going to drive it. You're going to make minor modifications. It's already got rifle racks (but that's a good thing in my opinion), an aftermarket radio, non-original tires most likely. Maybe non original shocks? Even as good as it is, it's not really 100% original anymore right now (but maybe 98% is better than most!). So make the changes you need but don't throw away the old parts.
Therein likes the one issue many have with having to take into account the future value. A small (or big) pile of old parts that you can't get rid of, but trip over every time you turn around. Do you have space for it? Maybe a separate out-building or dark corner of the garage where nobody goes? Then you're set.
In that situation you can make all the bolt-on changes you want with impunity. Keep the old springs. Keep the old shocks (are they original?). Keep the old seats. Keep the old brakes and steering components. Keep the old everything and put all new stuff in it to give you a better driving experience.
As it sits now, most people would not end up driving it as much as they thought they would. At least not far from home. You could take it as is and bop around town all the time and still have fun, but a long trip to a show would be a lot more enjoyable with better seats, carpeted interior, better tunes, insulated top and sides and doors and floors, so that the noise and summer heat doesn't ruin the experience and piss off any spouses or kids you are taking along.
If your truck had 20k miles on it, I'd say leave it and don't even buff it out. But it's got 100k miles on the clock, dents here and there, and probably the usual changes in parts for it's typical lifespan. So I say do what needs to be done to accomplish what you want. If the most important aspect of it is value, then that's the unknown really and you should put it in a dry shed and leave it alone for a few years. Maybe down the road a mostly original one will be worth more than a restored one. But right now restored gets more money than original for most owners. Unless you have some rare example.
Whether it will win any shows as it is all depends on the show. And the people.
And the same actually still goes for resale value when it comes right down to it. As said, unless you have some spectacularly original low mileage survivor with some special provenance, the higher value Broncos are the ones that have brand new shiny paint, new interiors, new engines, maybe fuel injection, and totally spit-polished undercarriages. Not the dusty barn-find that needs to be restored. That may change, or maybe already has. But it still seems like the big bucks go to the shiny paint.
I think that the 100k miles, the few mods already, and the general age of the running bits is limiting it's value as a special-original-rare EB.
In other words... Do the things you want to enjoy it yourself.
But keep the old parts that you change out.
Paul