What motor is this 327 or 350

[Kurt S]

From http://www.camaros.org/drivetrain.shtml#BlockCast - The 3959512 SB casting (not to be confused with the 3963512 427 casting) was mainly used for warranty / service blocks, though it did have very limited production usage in 69 engines. It is a 4" bore block, thus could have 302, 327, or 350 applications.

Yup, the block is the same, but the pistons and crank are unique per displacement.
Could be a 66 warranty block, but doubtful on the 65 unless he just bought it as a service part.