Welcome to the wonderful world of diy watch construction.
At best, replica watch cases are not made to any specific standard of quality. Their dimensions & form are dictated solely by what the factory may have available at any given time. For this reason, it is folly to assume that a gen movement (or any other gen Rolex part) will automatically fit anything other than a gen case (exceptions being a few $650-$2,000 made-to-gen-specs aftermarket cases from the likes of NDtrading, Yuki, etc). And even some of the best made-to-gen-spec cases do not always mate properly with gen parts. Building frankens is much more of an art than a science, meaning that the theory (of what should fit) more often proves to be the exception rather than the rule.