Other suggestions for upgraded components that I've used with a lot of great results:
Allen transformers (from David Allen amps).
SoZo caps for tone/coupling caps. A little darker than the Orange Drops, which can sound a little 'brittle' in some amp circuits. TubeDepot has these.
F/T power supply filter caps. These do the best job of keeping the bottom end 'tight', that I've found.
