Just remember that the difference in volume between a 50 watt amp and a 100 watt amp is not but a few decibels. But, to offer a suggestion, I'm gonna suggest a Marshall JCM 800 (like I always do). I got mine used for about $700, which is a steal for this amp.

Have you thought about one of those Marshall Powerbrake things? Contrary to what they say, they can be used with other amps other than Marshall's. A buddy of mine uses one with his Soldano.