I just did a fairly extensive search online for a Vortec TBI intake, and I can't find one! Looks like you'll just have to go TPI. Darn. lol /forums/images/icons/smile.gif
You actually just overbore the cylinders. Sleeving is fairly costly and hard even for machine shops. But you have to bore all of them if one cylinder is bad, so a new set of pistons as well. Don't worry, shouldn't be over $150 for a good set of pistons.
Really depends *why* its got bad compression. Head gasket? (side by side low cylinders would be indicative of that, since you mentioned a couple, not one) Heads? (burnt valves, stuck?) Or maybe rings? (*should* smoke)
If you are getting the block for free, tear it down and see what it looks like inside. The reason for low compression should be fairly obvious, just make sure you know which cylinders are bad before tearing it down, so you can check them closely.
Don't know about the Holley working. I'm assuming you are saying ditch the Vortec heads, but AFAIK, there is nothing special about Vortec blocks/pistons, etc, other than probably better parts (rods probably for one) and of course the Vortec heads. Again AFAIK, since Vortec heads bolt to older blocks, the opposite should be true, old heads should bolt to a Vortec block.
As to EGR, I'd run it. Having never inspected a Vortec motor, they had to run EGR, and the only way to get the exhaust gas was via the exhaust manifolds/pipe. (witness the EGR Vortec head kits, from Corvettes perhaps? They are on the SDPC web site) So if you get the entire thing, including manifolds and EGR, it should be a pretty easy swap. If you swap heads though, you'd just need ones with the center heat crossover.
I've got a TBI intake if you need one, should be a 1988, but I can look closer if you are interested. PM me if so!
I'd run EGR, (and I'm going to) but thats me. Better cruise mileage, no power penalty, and more resistance to detonation, not to mention "legality" should you ever need to move or sell the truck. I'm really not far enough into my buildup to worry about EGR yet, I'll probably order the "kit" from SDPC with my manifold, but I should research where they get the parts from to make it, might find donors in the wrecking yard.