3.5"' lift and 1-2" BL should be good for 35's and some decent flex room.
The caster on these is adjusted with bushings that go between the axle and the radius/control arms and dont require the mounting location to be dropped.
With a 3.5" lift most run a drop pitman and drop track bar bracket but others including myself (I have a 76 so it has a little different stock track bar bracket) are using a riser off the axle to relocate the track bar instead and usually use a stock pitman arm too. I think this differs if you have a 66-75 or a 76-77 because of the track bar mount.
Broncos come stock with cv shafts front and rear...yippie!!!
A lot of guys run extended radius arms (extra 10-12") (or extend them themselves) to get a lot more travel out of their suspension.
I'd extend the brake lines, you can get them from the vendor you get the lift from or off ebay. Rear driveshaft should probably be extended or replaced if you are going to wheel it a lot (Tom Woods is awesome for DS's)
Axles are pretty good stock and with 35's should be fine, they do sell alloy shafts for the front (not a larger spline, just stronger) by Yukon or any of the other major makers out there and the rear is often upgraded to 31 spline on those who wheel a bit more often. The 9" carrier needs to be changed for this but you can also get one out of any non Bronco 9" and they will be 31 spline. And gears, 9" doesnt require a carrier change for any set but the front if going from 3.50 (typical stock but not all) to 4.10 or higher will need a change.
You can check out my build thread on my wheeler by clicking on the Stretched 70 in my signature, I definitely dont know all the answers but I have learned a ton from this site and from just doing it.
BTW - good luck with your purchase, glad you have found the other side ;D
That is a good starting point. To clarify some details...
Broncos came with a ford 9" rear axle with 28 spline axles only. 31 spline is aftermarket. didn't come from the factory that way until '78
The front axle is a Dana 30 or 44. Don't trust the year, they tend to get swapped around. 4 bolts hold a kingpin and usually indicate a dana 30. one big nut is for a ball joint, dana 44. Stock Dana 44 axles have little U-joints on the axles. Look at upgrading these. Dana 30's last fairly good in a Jeep but die rather fast in a Bronco if abused.
Gears, lockers and transmission could be discussed forever. Pick what you can afford and approperate.
Driveshafts come factory with CVs, watch the angle of the rear CV, it is easy to go too severe without knowing it.
Lifts are basicly a set of coils and bushings for the front and leaf packs out back. Blocks and add a leafs are not the best for a bronco but have been used. Getting fancier starts adding longer/relocated shock mounts front and rear, longer arms in front. Don't forget the brake lines. Some form of adjusting caster after lifting. Common method is C-bushings. Long arms also do it with some built in caster correction. Severe cases may need to have the knuckles cut and turned.
Modern technology works very well on early broncos (soft springs, EFI, computer controlled transmissions, etc.).
For 3½" you should look at drop pitman arm or heim joint steering but only when matched with drop track bar bracket or the better track bar axle riser bracket. Basically comes down to if you change the track bar, you need to change the steering as well. You can get bumpsteer that is a real pain.
Other things to research; power steering, 351W, hydroboost, disk brakes (mostly for the front), death wobble, axle wrap. I am sure there are a few more common things, just can't think of them right now.
