Pre Bs do not have a firing pin block but that sounds like a transitional which may or may not have a FBP depending one when it was made. The lack of a FOB will generally make for a nicer trigger as will buying an old, well worn 75.
C.A.I. Was one of the original importers and there are lots of CZs out there they imported. Does not affect anything and is not concerning.
Price wise, if its in good condition that sounds like a good price. Beat up looking ones on GB (some of the best shooters IMHO) can be had for about $400 + fees, shipping and transfer as a comparison.