55.2-59 changing drivetrain for 1958 Apache 38

[studeclunker]

Okay, I tried a search... I did, I did! Came up empty.

Okay we have a '58 Apache 38 (One Ton?) It's in great cosmetic shape and runs well. Needs a fuel pump I think. Top speed on this truck is about fifty MPH. I would like to have a more practical range for this. There is a '70's 350 in the shop with a manual 4spd. I also have an '80s motorhome carcass with a good 1 1/2 ton rear end. Would it be possible to swap out the original drive train with what I have available? Sadly, I'm sure the floor start will be lost. We would like to put this old truck back to work. The six and present setup just isn't practical.