Welcome to the site, 30Below. As for your particular car, I'd say you could benefit building it either stock or modifying it some. The best answer I can tell you is whatever you decide to keep off the car, properly label it and put it in a dry storage place. As for engine modifications, if you want to go more wilder than what the 340 can offer, pull it out and stick it on an engine stand off to the side of the garage: then drop in whatever engine you'd like and go as crazy as you want to. I'm in your same situation, except mine is just an original 318/auto car. (You definitely have a more desirable engine/trans. combo from the factory.) I'm putting the lowly 318 off in the corner to receive a rebuild later on and just sit until I decide drop it back in and go 100% factory correct. For now, I have acquired an era correct 340 (still need a built 727 to back it up), changed the color to something I felt was more appealing, and I plan on going wild with the 340. It's just stuff that can all be changed back to original, so why not? Good luck with the restoration or resto-mod.