I've seen people do all sorts of amazing things with cars and trucks and pull them off (and almost always with LOTS of extra hassles you would NEVER imagine being a problem involved) AND I've seen lots and lots of people trying to do the same thing, trying to pull off some wild engine swap or even a "body swap" like you are talking about (and that's pretty rare since these days since so much is now "unibody" vs "body on frame" with the separate frames) but while I'm not saying don't do it, hey its a free country and as long as something is still legal AND fun (less of that left each year!) we can do whatever we want. IF you pull this off though, your reward would be whatever good feeling you get from doing the work, but don't expect it to be worth a whole lot money wise and I don't know what other stuff is going on in your life and I'm not asking either, just sayin if you've got a wife/gf/old lady, etc don't expect her to be too happy when you say "I'm going out to work on the truck again!" let's just say it can put some "stress" on that relationship (haha!)
So, basically if you REALLY love wrenching away on something you're not sure will ever even work, or if it does, who knows how its going to drive, don't want to find out you forgot to figure that in at 75 MPH when it starts swerving all over the highway and last thing is, even modded trucks, cars, bikes, etc that turn out great normally don't even end up being worth as much as a stock model unless you get really lucky and find the right buyer! I worked in used car biz for a while (we sold new Mitsu's too, like anyone buys those!) but same owners had new Honda store next to us and we could sell all the barely used Honda's we wanted, which are damn easy to sell but every so often some guy comes in with modded up Civic Si or Evo and I swear it was SAME THING EVERY TIME, guy starts running his mouth about how much he spent on the intake, exhaust and on and on and we'd have to cut him off and break the news, sorry man but those mods you spent that $$ you should've bought a house with or something, they make your nice ride worth LESS to 99% of buyers! I'd think long and hard about your idea and not saying I'm any different, I've had all sorts of them too, but think before you jump!