^X2. Just like working on Blasters...if you do it long enough, you'll wind having just about every spare part on hand you'll be needing. Cars aren't any different. If you stick with one brand or platform in particular, pretty soon you'll see what usually breaks/needs attention and what works fine year after year.
Oh, this is just random, but watch out for projects with blown head gaskets. Sometimes you get lucky and all you have to do is replace the gasket. Other times, the whole head and/or deck is warped or cracked and its $$$ to fix properly. Every time you do a head gasket, you have to check for warpage and cracks. Plus you often need a torque + angle gauge to cinch the bolts down correctly.
My .02