50 are correct since I could come up with 50 original cars assembled, the very first Bob Tucker's autumn Gold Z-11 assembled in August or Sept of '62. The last Z-11 Was Brian Batchelders car in late Feb 1963. I heard Joe Padula & Dave Kenahan from Providence RI (Norwood Chevrolet)ran their 1963 Bel air 2 door sedan car with over the counter aluminum nose, QM short block and Z-11 heads and intake. Sure rattled Billy Lawton (rest his soul) from Tasca Ford in his 427 Fiberglass Galaxie at most Eastern Seaboard S/S drag meets
You often see the total number of Z11 cars built listed as 57, but I notice that most of the people like you that seem to know things point to the number 50 so that's the number I'm going with.
There were exactly 50 crate engines built for the 50 production cars. I have the exact number of partials built also. Not many. Dick, Robert or Phil I'm out of town, you might have the docs handy. Either way it was not many. Can post more next week if anyone is interested.
I don't have it in front of me either but the Chevrolet by the Numbers book shows a copy of the GM engine plant's records showing 50 full engines and 20 half engines. I think it also shows one Z11 engine or maybe half engine went out in 1965.
I'm guessing a half engine is the short block assembly?
I don't imagine there would be any record of the number of cylinder heads and manifolds sold over the parts counters. I gather that these parts were a little hard to get so I don't imagine they would have sold a lot.
I think I read somewhere that a few of the lightweight 62 Impalas might have ended up with Z11 top ends but apparently they all left the factory as regular 409hp 409's.
It's amazing that most of the Z11 cars and lightweight 62's have simply vanished without a trace. I guess at some point they were just used cars with no real value.