I believe the 350 will bolt up replacing the V6 with no problems other than using the plate from the GMC pressure plate and bolting it to the 350 pressure plate to bolt up to converter.
In 1975 I put a 67 Chev 283 in a 65 GM (V6) carryall which fit except the above mentioned.
Anyone aware of a potential problem with the couple of years newer.
I want to use the GMC 3 speed automatic if possible and don't know of any potential problems.
Thanks,
Ophart