GP9's, SD9's and F9's came new with 567C engines whereas GP7's, SD7's and F7's had the 567B engine. I think (not sure) that E7's and E8's had "B" engines while E9's had "C" engines. The "B" and "C" are easy to tell apart as the "B" (and the BC) has rectangular airbox covers while the "C" as well as all 645 and 710 blocks have the round covers. The "BC" was a conversion kit applied to the "B" block. I may be wrong about this, but I think the straight "B" cylinder heads did not have any water flow through them whereas the "BC" heads do have water passages in them. I don't know if the "BC" and the "C" cylinder heads are interchangeable. The idea of the "BC" upgrade was to impart some of the advantages of the "C" design to the older "B" blocks.
While many "B" blocks did get upgraded to "BC", there still some running around that are still straight "B" engines. It seemed to be mostly a policy of the individual railroad; for example GN had a lot of "B" block engines at the time of the BN merger in 1970 whereas the NP converted most of theirs to "BC". EWG has ex BN 1617, exx CB&Q 261; a GP7 with it's original 567B engine. Obviously the "Q" didn't convert all of their "B" engines. BA&P 301 is a GP7, ex NP 560, and it has a "BC" engine. W&I's 316 is a rebuilt unit, classified as a GP16, and it has a "B" or a "BC" engine in it. Check this video and notice the rectangular airbox covers.
W&I 316 startup
I am aware of at least one rebuilding program, C&NW at Oelwein shops in the 1980's, where they basically didn't care what engines went into what carbodies. I saw GP7 carbodies with 567C engines and GP9 carbodies with 567B engines. Since SP's GRIP program dealt with mostly GP9's, I would suspect that all the units got rebuilt 567C's.
I got acquainted with the 3194 at Hunters Point during a visit in 2005. It is a sweet running unit.