Charles,
Yes I think this is going to be a nice sounding little amp and will be versatile with tube changes and pwr outputs.The JJ 2a3-40 tube is very similar in physical size of a 300b and shares some of the same internal structure with different electrical requirements.
We are using the Audyn Cap Plus as the coupling caps,these are very reasonable in price and Aric likes them for their natural and smooth sound.I will try them for awhile and then make that decision.
I've used The Jupiter copper foils before and those might be better.
He just uses standard copper hook up wiring internally and there may be some room for improvement there also.
As mentioned before Aric only builds his amps and preamps point to point with no circuit boards.
If I really like this amp,I may look into a build of Basically the same amps but in mono blocks that may utilize interstage transformers instead of coupling caps,not sure if that can be accomplished with the 2a3.
Kenny.