Slick 60's

I am planning a build of my 66' F-250 4x4, 390, 3 speed auto (c-6 I think). I've been searching for information on engine/trany swaps and was wondering what is the most realistic to meet my goals. I want a daily driver that can run highway speeds.
Go with a 5 speed transmission? If so what?
Swap motor and transmission for a later model powertrain?
Ive even looked at a cummins swap, but this seems tedious and expensive...

ANy ideas would be appreciated!

If your truck uses a divorced transfer case (i'm not a 4x4 guy, hope that is the correct term for tranf case separated from trans), you should be able to add a Gear Vendors Overdrive unit, this will drop your cruise RPM a bunch,and if you get the fancy electronic control, you can set it up to "split", essentially giving you a six speed:)

http://www.gearvendors.com/

PS: yes, they are spendy, but used ones come up f/s occasionally on CL, racingjunk.com, etc

Yep, divorced transfer case.
Thanks for the reply. I'll check out that site.

I drive a 65 f100 4x4. Stock 352 with 2 barrle holley carb. Motor is 40 over bore and has a set of long tube headers. It is a 4speed Np 435. Rear gearing is 3.56. I can run at hiway speed all day long. I dont have a tach on board yet so not sure what the rpm is but it does not sound like the motor is running at to high a rev when cruzing the highway. I would think I could get even better mpg out of it if I went to a 4 barrle carb and kept a light foot on the loud pedal. I would think your FE would be a fine motor to use. If your truck is still stock and a 3/4 ton rig your gear is probably a 4.56 which was a pretty standard setup for the 4x4. That will have to go if you are not going to an overdrive unit. You can use closed knuckle dana 44 front axle up to 72 it will be a direct bolt in same for dana 60 rear axle. Good luck with it good to see another 4x4 hitting the road. Factory 4x4s are a small group out here in slickland.

Edit: Automatic trans takes power to run and eats into mpg if that is a concern for you. Nicer to drive as you are not shifting all the time. The 4 speed is more like a 3 speed as the granny low is rarely used unless pulling a very heavy load or crawling off road in 4 low.