[truckster]

If you do decide to go the junkyard Vortec route there are a few things you should be aware of. It's pretty rare to find used Vortec heads that aren't cracked; my machinist got new, heavier castings for me for about $200 each. You'll need a new intake manifold (different bolt pattern) and flexplate or flywheel (Vortec has a 1-piece rear main seal). If you find one with the fuel pump hole drilled consider yourself lucky (I found one, so they're out there); otherwise you'll need an electric fuel pump. The temperature sending unit won't fit, but forum member A1971Blazer does a really nice job of turning them down on a CNC lathe. You'll have to do a little bit of massaging to get your accessory drive brackets to work, but they will. However, if you're considering a serpentine drive, it would be a good idea to pick one up from your donor vehicle. Your stock exhaust manifolds will work (I'm using Dorman 2.5 center dump rams horns on my Blazer). Your stock motor mounts will also work. Your distributor will need a mellonized gear (available separately, but included with many aftermarket HEI distributors).

On mine I'm running the HT 383 cam (more torque, plus it has the fuel pump lobe), a Cloyes double roller timing set, and I put in a bronze tipped fuel pump rod.

I think that's about it, but if you have any questions, just ask. Good luck.