I'm still interested in buying a Twin Reverb - certainly the price is much lower to buy a master volume one post-1972 as opposed to a non-master volume one pre-1972. I'm quite comfortable making modifications to amps, so if all that's required to put it back to earlier specs is to detach the master volume pot, then I feel like I could do that easily and save $150 to $200. Possibly the only downside would be that I'd still have that MV pot there, but it won't do anything, which could annoy me, but is probably worth the money I'd save. Are there any other differences I should be aware of between early and mid-70s twin reverbs? Build quality, transformer quality, sloppiness of wiring, other circuit changes, PCB vs eyelet board, etc?