I agree with leaving it stock if what you want is a classic original truck. But, I would do the same thing if I wanted to drive it all the time.
Think about it, this truck was built to toodle down country roads at 40mph, not compete with traffic on a freeway.
I'm in the same boat, I have 52 2-ton GMC dump truck. I got it running and stopping with the stock stuff, and it's down right scary going down hills and very slow coming back up. I'm looking at SBC swap and more modern axles, even if I have have to go a little wider to do it. Also to get rid of the wheels the tire shops here won't touch. I am reusing the original frame as its robust and already under the truck. swapping in rears is easy.
I say, let the museums have museum pieces, and make the drivers safe and pleasant to drive.
I used to have a 70 fastback mustang that was a beautiful car, and terrifying to drive fast, or panic stop.
