It's hard to say what YOU should do. Don't know YOUR budget, don't know YOUR tastes. Saw you were doing a body off and figured you were wanting all new stuff. Don't want to get into the issues of if these trucks can go 70-80 safely. Been in that post, brutal. We won't settle the rebuild or not idea, and prices are all over the place because of area, quality of parts used and machining/replacement needed after fluxing or dye. The price I quoted for 350 was TURN KEY at Summit. Others are quoting you bare block. You can get a new "crate" motor from $1500 on up to Turn key. That's another discussion. Some buy bare bones with valve train and go to O'Reilly's and get all the other life time warranty parts....and on and on. You can also get a good non smoking, good compression, V8 for $600 and refresh it with all the pumps, carb, chains and gaskets and clean it out and FLAPS lifetime parts. Total $1000 max. These issues of 6 or V8, speed and safety and buy or build, are very hard to decide. I have had no problems with putting V8's in TF. Power Disc front, update steering, stock suspension is fine, 60's-70's 3:73 rear end fits nice, easy to do, $250. Almost any GM transmission you want will fit the block/bell housing. Use any V8 you feel is the correct for YOUR idea of a cool truck. 265, 283, 305, 327, 350 and up to BBC.