Vortec heads have excellent flow potential plus super efficient combustion chambers, but lack exhaust crossovers so hopefully you live I a warm climate or don't plan on using it in cold Winter months. Heat is your friend with these things and why all wet-flow systems use a heated intake manifold.
LOTS of places to screw up a good SBC build so I'll cover a few things I see nearly EVERYONE do to them that yield negative results.
NEVER use a high volume/high pressure oil pump. It robs power and wears the distributor gear out much faster. I've also seen oil pump drive shaft failures in cold weather with thick oil in the sump.
Do NOT use a "double roller" timing set, at least 95 percent are JUNK and even the better ones get loose and start flopping around as there is no tensioning system for them. I use and prefer the stock link-belt Morse chain set-up. The early 3/4" wide versions are still available and USA made. I just grabbed a mint condition TRW set with 3/4" wide steel gears off Ebay for a build that's coming up here......$28 shipped.
Establish tight quench. Shoot for .035", never over .040" for any reason. WAY too many folks don't check deck height and ALWAYS put thick "rebuilder" head gaskets on these engines. Many aftermarket "builder" pistons can be WAY down in the holes at TDC, some to and past .030". Combine that with a big thick composite head gasket and you've just built yourself a "turd" no matter what else you do to it. You need to check deck height, deck square and combine head gasket thickness to get into the range above, but it is not optional for one of these builds if you really want the best out of it.
Use a stock cam in it or something very close to stock with longer seat timing and gentle opening/closing ramps. Yes, the CS-274 cam (basically a duplicate of the 350/300hp cam is the best truck cam out there. Most folks jump right to the "RV" cam, 204/214/112 LSA but they have lowered the compression and put so much squish area in the engine they just build a big "turd" instead of a powerful smooth running efficient set up. The stock cam LOVES 9.5 compression, I've even ran them higher than that on pump gas with tight quench w/o issues. Smooth idle, tons of vacuum, good fuel economy and butt-loads of power right where a truck engine needs it. If going roller there are several roller profiles very close to that cam, just avoid the ones that are ground on tight LSA's. GM offers one in particular on a 109LSA, it's not that great so I'd avoid that deal. I wouldn't go tighter than 112LSA and around 194/204 @ .050" or even a single pattern cam is fine with those heads.
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