Just some options...
Is this a "hot rod" or a daily driver? Power performance or just a cool running pickup. Pick the best engine and don't overlook the "excentric' extras like the decision to modify the front clip....I installed a Jaguar front clip into my 57 GMC for about $600....but it took some time and it was fun to build. Rides like a dream.....327 V8, 700R4, Ford 8.8 RE, PS, PB and A/C. Bucket seats from a Honda which are very confortable and a floor shift in the consol...just a daily driver.
This is your truck...make it yours! You can do either item mentioned as long as "you" are glad with the decision. Just for the fun of it, decide on your options...leave all options available until you decide what you are going to do. Then have a great time building your truck just for you!