I've got my hands on a 54 f100 that's been in the family since new. It is in great condition. The problem is the low gearing. How and with what could I change the gears out with to get better hiway speed? Would like to keep the original rear end in the truck if possible.  

I have a 55 f100, when i purchasedthe truck it had the original rearend,393 if my memory serves me, but i got one from a 72 half ton and it fit right in, you would naturally want to get new u bolts. The rear end i put in has 3.25 ring gear. it moves down the road nice.