Casting Number / Engine Size

I recently bought a motor and I was told it was either a 283 or a 327 out of approximately a 1965 Vette. I've researched all the numbers I've found on the motor and all I can tell is that it might be a 327 or a 350 from the late 60's or early 70's. The main things I want to know is what year it is, what vehicle it was originally made for and what size it is (283, 327 or a 350)? ... Mainly the size though. Below I'm listing all of the number and places I've found them and see if anyone can decipher them for me. I wrote down the numbers as closely to what the appeared to be as possible.

I believe these letters/numbers were on the front of the block.
C4F415069
V03061JC

I think these letters/numbers were on the top of the manifold
340234 R
B274

These letters/numbers are on the back of the block
GM21
3970010

These letters/numbers are on the exhaust manifold
GM336710

These letters/numbers are on the block inside of where the bell housing mounts to the block.
010
020

509
H18

PS78
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