That's good. Are the circuit/parts values, etc., the important little stuff the same? How about cab design? Obviously the speaker won't be the CTS but similair character? Altec style upgrade? A friend of mine (drummer's) kid has a peavey practice amp that I got running and gave to him with an Altec 421, I think B, not A in it. Not sure what that means but I put it in there and messed with tuning a bit. That one sounded the best because it was loudest. Big, heavy white castframe thing. Could swap speakers with him. Delta15 has good profile for this amp too. Obviously it would make sense to read through the entire thread, pick out the technical bits, etc.