Not to undermind your capabilities, but your far better off with something from the factory with 100k miles on it, then something you have pieced together, unless your going full modified.
Any reputable wrecking yard will have compression #'s as well as the vehicle milage it came from, if its a pull your own type of place...Go for the crunched vehicles....at least you know they were moving, I laugh when people tell me they got a "tranny" from this cherry caravan, looked like it had been garaged all its life, what a score !!!!......hmmm, why was it in the bone yard I wonder ???