I had an OLP MM bass which was very similar indeed to the MM4 kit bass. I replaced the stock pickguard with one designed for a real MusicMan. The pickup location was a few mm different to the original (a bit nearer the neck IIRC) so I had to redrill the pickup fixing screw holes, but otherwise there were no issues. Plus the pickup was now in the correct position for a real MM sound. I'm sure the bass sounded better after the move.