...I’d like to be able to drive 70 mph on the highway and not have to wound up/loud.
4.11 puts you at approx. 2300 rpm @ 70mph with your combination. Not really a bad place to be with what your engine sounds like it will be able to do.
At 55 you're down at 1800 rpm, which is pushing the lower limit a bit actually. But since the wind and rolling resistance is quite a bit less at 55, you may still be able to do it well, if the engine cooperates.
At 65mph you're into the 2100rpm range, which sounds pretty good as well.
Some of it will still depend on the cam of course, but with the Sniper, headers and cylinder heads, with the right cam you can pull the lower rpm we're talking about here.
Remember your stock setup would have run approx. 300 to 1000 rpm higher at those speeds, so even though the gearing may sound low, it's actually quite an improvement, street-wise, over some stock setups.
A decently quiet, but still easy-breathing exhaust and a lot of thought to the interior sound insulation will be a huge part of how happy you are with the "performance" as well. The noise inside an un-insulated Bronco is epic in scope, for those not used to old rigs.
But mostly I’ll just cruise around 55mph. I want to be able to drive it from my House in N Texas to Dallas if needed without any issues. Approx 1 hour drive.
Should be ok I would think. Easy cruising, but might pop out of OD quickly once you hit a larger hill. But still not out of line.
Using the stock 302, but completely rebuild, aluminum heads, shorty headers, Holly Sniper throttle body. I’m not sure about the cam, but I can find out.
Interested to hear what cam you end up with. So many out there and some choices are fine for a 302 in a car, but as was said, how things react in a Bronco going down the highway is a big step away from what you would experience with that same engine in a car.
So 4.11's would get you there. But if you can't honestly say that you're never going to add larger tires, then the choice just got harder. At that point, if you're even contemplating larger tires down the road, a 4.56 choice would not be out of line.
And as was said, by all means put off doing the front until you've already lived with the rear for awhile, if that's an option for you. This way you haven't wasted two sets of gears and their associated costs if you decide it's not the right ratio for your needs/engine/tire size.
It's certainly easier on the brain to just do it all at once, and easier to do it while it's out of the vehicle as well. But since you're not likely to need the front wheel drive for any off-roading in the near future, maybe doing the rear only is an acceptable trade-off?
So I'm on the 4.11 side for now (until further notice...
).
But if in doubt, there is always the 4.30 option.
Good luck.
Paul
