:) Thank you for the encouragement. That's good information to know. I've got a hand wired prototype, and it seems to work ok, so my PCB is going to be similar.

That's one nice about (tube) guitar amplifiers: max current is at the power supply pin, about 72ma, despite transferring 27w or so. So your voltages are pretty high , but your traces can be pretty thin. The big thing is leaving plenty of space to prevent arcs.