1964 chevy k10 confusion is it a 350 or 327?

[cameyer]

hello all I am brand new to this site and the chevy ownership and very confussed about my new purchase. I am 18 years old and just bought my own car it is a 1964 chevy k10 pick up. I was told that it is mainly original I've crawled around and checked everything out....12 bolt rear dana 44 front sm420 t221 transfer case and all that checks out with being original but I was told it was an original 327 in the truck however I can not verify this. In the engine compartment two sections about 5 in long and 2 in wide have been taken from the frame on the driver side and one section taken from the passenger frame which i am not sure but i would guess use to be old locations of motor mounds leading me to believe the engine is not original. the engine is also fairly far back so i can not see the casting number in the back but up front the id number is VI2I3YS i have no idea what engine this is someone please helppp