Robert,
The master volume is a very valuable asset. I'd keep it, though it's not original. In my opinion, it's one of the most valuable things that you can have on an amp, if you're recording at home, or want to track in a room with an amp that's working hard at low volumes, but with minimal bleed. Mind you, the preamp section will be doing most of the overdrive work, but it's still one of the best compromises between a small, low wattage amp and getting THD Hot Plate or something like that. Plus, you can mess around with the preamp tubes to install 12AT7's to make the preamp section work harder when you turn it up.
Old Traynors are pretty good. I had an old YGM-4 StudioMate (4 8" speakers....8" speakers are getting insanely hard to find these days). The only downside to Traynors is that they were often bare bones--ie: no overdrive. There was actually a mod that could be done to some of the Traynors in the tremolo that could turn it into an overdrive.
Some mods you will want done to amps....I had a new grounded plug put on one of my old amps, because I fried myself every time that the grounding was weird in a live PA!