I might be wrong, but I don't think Mules would be any less bright than the '57 Classics. Stormy Mondays? Probably the same problem. You could go the P-90 route with Manahattans or MQs, but it's a very different sound.
It's a tricky one. 250k pots is a good idea, but being Gibson the volume controls might already be 300k.
Aluminium tailpiece? It's a subtle change, but it certainly makes the acoustic tone a little warmer and, to use the word you mentioned, woodier.