Update: 1971 Z28 LT-1 Block, Heads, Valve Covers
Here is an update on the casting numbers.
Back corner by the bell housing. (3970010) It is a 010 high nickel block.
Front tab after the vin. (V0309CGP) 330 hp LT-1
Head casting numbers on both heads. (3973487) large chamber 75cc 2.02 Intake 1.6 exhaust used on 71 & 72 350 LT-1 the heads were milled ten thousands back in 77, other than that no work has been done on the block.