Since you're committed to the pickup, I'd follow the path early hot rodders and strip off the bed and the cab. Sounds like they're pretty rusty anyway and you won't have to fix it. Sell it and you can invest back into your project. By the time you're done gutting it, it won't be worth much anyway. Getting rid of it ahead of time, you'll be ahead.
Make you up an aluminum floor, and a steel rollcage, and mount up just the bare necessities to make it run and drive safely. You're 318 might be enough, but a big block would be better. Put on a set of slicks and a semi aerodynamic body, and end up with something like this:
View attachment 1715464548
Instead of Model T based, it'd be truck based.