The guy that bought my 6V6 x 2, 2204 type head brought his band over to try out amps---- they played a Motorhead song while they were there----- the bass player was going through my Metro 100 watt MV head (KT88 x 4) when it was still in mostly stock 2203 configuration.
One way to go about building a bigger amp is to pick up an old Sound City 120--- gut the orig circuit and use the big orig iron and EL34 x 6 with the preamp of your choice---- you get a very solid steel chassis with plenty of pre-punched holes for the preamp tubes so you can configure almost any preamp you can come up with.
The output section on those amps is powerful and great sounding---- I think the 120 watt rating is very conservative with these monsters.
More power than most people would ever really need----- this is the output of one of the Hiwatt preamp SC 120 conversions I did early on:
Sometimes these old amps can be picked up cheaply.................. gldtp99
PS: The owner of the SC 120/War Elephant (high gain single channel) amp I did says it "Comes Through" in live rehearsal/gigs better than other big high gain amps he has----- "Power" has a way of penetrating, and can be heard/felt, without being blastingly loud in some situations------ but Power also penetrates through walls, ceilings, floors, etc and can get the police called on you sometimes.
. Try and find a 4x15 Cab for that Superlead and move into Lemmy territory!