Scott, there were no 327 blocks that have 4 bolt mains. There are 2 different main bearing sizes between the early and late style.
I don't know that the factory did or did not make large journal 327's with 4-bolt mains, but any 4-bolt main 350 block can take a large journal (307 or 327) 3-1/4 crank and become a 4-bolt main 327. If I remember right there were one or two years when Chevy sold large journal 327s and the 307 was available even longer.
So strictly speaking, there could be 4-bolt blocks that are 327s even though they may not have been from the factory.
Buying used 30 and 40 year old motors you really never know what someone may have done...
