Motor ID - casting number and suffix disagree?

[Portland68]

Hey all, looking for some help identifying the motor in a 67 C20 I picked up recently. Casting number appears to be 3970010 (302/327/350) but the stamping on the front is (partial vin?) 161180474 and then K03 09 CM.

From what I can tell that means March 9th, Ontario plant but the only hits I get for CM are for a 283.

Any idea on what the correct displacement is? I will be selling the motor locally but don’t want to mislead someone one way or another.