I am going to drop one of Metropoulos'Super Bass boards into my Super Lead.

I am going to do it anyway,but what is the difference?

I'm not sure about the 100 versions, but I have a '69 small box 50 watt head that is actually a model 1986 bass head. When I sent it to Victor at the Plexi Palace he noticed that it was the bass head someone had modified for guitar. He mentioned that if he returned it to original specs it would essentially be a JTM-45. I poked around some schematics on the web, and also asked some questions on some other forums and that was the general consensus: the model 1986 is essentially a JTM-45 with el34s instead of KT66s or 5881s and a solid state rectifier instead of a tube rectifier. Victor reccomended restoring it to original specs, and I implied that he liked that sound better. I'm glad I had him do it. I can plug into the lead channel alone now and get a great tone - I no longer have to jumper the channels to tame the ice picky highs of the lead channel. Some other people mentioned prefering the bass model for guitar as well. I assume the 100 watt versions would have a similar change but I'm not sure.

As it was described to me by my amp tech, the difference between a Superlead and a Superbass are essentially a few cap and resistor values that give the SB more low end oomph. Conversion back and forth is fairly simple if you're handy with a soldering iron.

My understanding is that the Super Lead has a split cathode pre-amp and different tone section and output stage values. I believe it also has a brite cap to keep it from sounding as dead as a Super Bass at low volumes.

To my ears the big issue is making sure the cap values are where you need them for your set up (sometimes Strat players get them swapped out for different values) and that the transformer is pushing out the correct vdc's to the plates, otherwise the amp won't have the same sweet spot. I have one of Greg Germino's Lead 55s which puts a lot more volts to the plates than typical 50 watt plexi. It makes the amp feel like something between a 100 watt Super Lead and a 50 watt plexi. The sweet spot is a little hotter, about 7 1/2 or 8 on the dial as opposed to about 6 on a Super Lead, but the amp is more percussive and responds a little more directly. The downside is that I'm cooking the tubes a little hotter, but I can live with that. I am very seriously thinking about picking up one of his Headroom 100s voiced for Super Lead (he offers both version), but I don't really "need" it at the moment and its hard to justify the expense.