Block drain plug on the left side. I use brass, or a brass draincock.
Core plugs on each side, (use 242 "blue" Loctite thread locker for sealant) various plugs front and rear. Some front plugs are vented, but the replacement plug kit doesn't have vented plugs. They're solid, non-vented. A REALLY SMALL drill bit (about 0.032) fixes that.
DO NOT forget the threaded plug that would be on the rear of the block, china-wall area, partially covered by the left cylinder head. Head comes off to fix that mistake.
Oil pressure sensor often with an extension or tee near the distributor hole.
There's also a soft plug in the oil-filter passages, but the machine shop has probably replaced it already, assuming they removed it to begin with. Failure to have this plug in place means the oil filter does nothing--oil bypasses filter.
A 4WD vehicle will have a plate between block and engine mount bracket that the strut rod going down to the transmission attaches to.
Front of block--ahead of "fuel pump" boss--gets a bolt or two to seal what used to be motor-mount bolt holes back in '55--'57.
Two dowel pins on each head-gasket surface. Older engines get two dowel pins in the timing-cover surface, but I think Vortecs have those holes open and the timing cover has molded-plastic teats that go in those holes. Two dowel pins to align transmission at rear of block--but nobody ever takes them out, so they'll still be there.
Cam bearings, but most machine shops install them before they give the block back to the customer.