My Dad had a '68 long bed, 305 c.i.d., 3 speed on the column. It was a shop truck, and this was in the mid 70's. That damn thing lasted forever. I used to run for parts in it for the mechanics at the shop. We also used it to tow in customer's cars, towing the boat, etc., etc.
The shortbeds or the flaresides look a lot better IMO. I think you can pick these up pretty cheap now, but an awful lot of them are rust buckets. However, you can buy very cheap aftermarket sheetmetal for them as long as the bed floor and cab aren't rusted out, go for it. The parts are plentiful and cheap.
I had grandiose ideas of hot rodding a '59 Chevy Apache truck about 5 years ago. I bought one for like $2000 or so, maybe less, and it was in decent shape but someone somewhere along the line had replaced the steering with a rack and pinion and they did a real hack job on it. It wasn't worth the effort to try and fix it, even though the engine was already replaced with a 350. After driving it a year or so, I got tired of it and sold it.
The closer to stock the truck is, the easier it will be to work on, besides, you won't have to pay for some other person's ideal of what is cool.
Good luck and be patient!