Several folks have done benchmarking tests suggesting the M1 macs are 2x to 3x as fast as the older Intel macs. See Performance benchmarking FM18 Intel to FM19 on M1 - #15 by xochi
Since the single-core performance for all the M1 chips is fairly similar, it's likely that spending the extra $ for M1 Pro or Max wouldn't help much.
As for RAM, I think you would want at a minimum 2x the size of your database, e.g. for a 4GB database file I would want no less than 8GB of RAM. I think 64 is overkill, but 16 or 32 would be sensible.