You don’t have 64 BSIC’s, because BSIC = NCC & BCC. The NCC is the network country code, which was allocated to your operator by the telecom regulation agency. Normally, you have only 1 or 2 NCC’s (right ?). Then you have only 8 BCC’s to play around with (from 0 … 7)
But still : this is plenty enough to avoid problem.