Hi Jason. I’m not an expert, but I have a CTB block (that I believe is genuine) in the garage and I think the suffix stamp looks different from the one pictured here. The gap in the C and particularly the B… I also agree that it would be unusual to have an OH built car sold new in CA, but I’ve also heard that sometimes that happened with low volume models and maybe even because of the unique build year in 1970.
My block, FYI for the stamp comparison:
https://www.yenko.net/forum/showthread.php?t=174868
Just MHO,
Anthony