Re: 350 engine identification
I found this as far as the block casting goes.
10105123 350ci Bare Block
This engine block is used in 1986-99 Gen I heavy-duty applications. It has 4.00" diameter cylinder bores and four-bolt main bearing caps. This block is machined for a one-piece rear crankshaft seal. (Does not include rear seal or adaptor.) These blocks weigh 181lbs. Technical Notes: Cylinder wall thickness is the same as current production engines. The lifter valley is machined for hydraulic roller and flat tappets. Crankshafts with two-piece seals can be installed with adapter P/N 10051118. (Block casting P/N 10243880 or 14093638.)
10243880, 350, 95-96, 2, Goodwrench Crate Motor. 14010201
10243880...350...95-00...2 or 4...Vortec truck, Gen.I crate motors and "ZZ4", roller cam, one piece rear seal.
For the head
10125377 Cylinder Head Assembly
This is a cast iron cylinder head assembly used on 285 hp 350 engine (P/N 12353641). This complete cylinder head assembly includes 1.94" intake valves, 1.50" exhaust valves, valve springs (P/N 3901068) and valve spring caps (P/N 14003978). Technical Notes: This cylinder head has 64cc chambers. The cast number for this head is P/N 14101083 or 14096217. This cylinder head has 1987 and later inlet manifold bolt pattern. The center two bolts are at a 72º angle.
You apparently have a '95-'00 Vortec 350 cid 2 bolt main 285hp first generation block with one piece rear mains and 64cc heads from a light truck (P/U or SUV).