I'm in the process of purchasing a:

79 Bronco
460/C6
6" suspension lift
38.5x16-15 Swamper TSL's

I'm told the Bronco still has 3.50 gears. This vehicle will spend most of its life on the highway or gravel roads, not much on the trails or mud. Will this gearing be ok since it does have a 460 or should I regear once I get it?

I have a 429/C6 on 36" swampers, with the stock 3.50 gears, and get around perfectly fine. However, for you, I'd suggest running 4.10s. Basically, drive it around for awhile, see how you like it. If you feel it's sluggish from a stop, or doesn't feel like it has to top end you think it should, then you can plan for the 4.10s

I am running 4:56 gears with my 38's and at 65 MPH I run about 2700 RPM's. I have a 400/c6 in mine...

Gearing like 3.50 with really tall tires puts a heavy strain on the transmission(if its an automatic,hurts the clutch with a manual).4.11s would give it a little bit of a break.

i think you'll find the bronco to be a little bit of a dog in the start. but it wont run at such high rpms. i have a 78 with a 460 and 35inch tires and 4.56 gears and a 79 with 35inch tires and stock 3.50 gears. needless to say. the 78 gets better mileage. i'd prefer to do the gears in the 79 if i had money...but thats just me.

4.10's would be best I think. I agree with the warning about transmission wear running 3.50's with 38's. My kid's 78 has 4.10's and 38's with a 400/C6 and does everything pretty well. Mine has 4.56's with a 460/C6 and when I run 38's it goes right through the gear ranges on the street, 2600rpm @ 65mph. My Bronco is 1000lbs heavier and runs on 44" tires sometimes, so it's a compromise for me.