Thank you for the welcome and the advice.
I'd love to be able to send this out and have it repaired/ restored, but tinkering is part of the fun and part of the challenge.
It's great to see that there are ways to keep these amps 'alive' and also upgrade them to perform better than they were ever intended.
My current plan is to get the thing working first, then make the upgrades. It currently powers on the lights and the dials, but it makes an awful hum so I don't keep it on for very long.
I'll post photos soon.