Mesa Baron-what tubes?

Buying a Mesa Baron and the fellow selling it told me that Mesa suggested leaving it stock and not having the mod done for EL34's which can be made to work but that the bias of the amp makes it not the way to go.So what about this 5881/6L6 tube.I believe the amp will accept 6550's or KT88's but man 12 tubes-it is gonna run some big $$ with the latter.Any input?