Hi Tom,
First off, i suggest getting a Thiele 1x12 cab. it will really fill the sound out.
as for changes, here is what i did to mine and im really happy with it.
replaced the c90 speaker with Eminence tonkers, changes some tubes around, v1 is a tungsol gold pin 12ax7, the reverb driver is a NOS 12at7 mullard, the phase inverter is a groove tubes Matched PI 12ax7/ecc83. Groove tube 6l6GE's in the power section.
the other gain stages are regular Tung sols. i added spring style tube retainers for the power tubes, Im not suggestion you do the same but it is a great amp, i only set mine up to suit my tastes. I get a great fender style clean tone and amazing gain tones. you will love this amp for a very log time.
sd