Stax CA-X -> CA-X Pro. Is it a crazy idea - or not?

[oldmancoyote]

Hello all,

I am about to become the happy (?) owner of a Stax CA-X (and DA-80). The pair are functioning, and actually don't sound that bad, but I have plans...

At the very least, I'm going to replace the more perishable parts (electrolytics) and possibly the power devices on the DA-80, as suggested by EchoWars in a thread somewhere. So far, so good. And theoretically easy.

However, still thanks to EchoWars, I now have the schematics and parts lists not just for the CA-X, but for the CA-X Pro: different flat amp, with DC-servo circuitry. So I started thinking... what if I created a couple of "pro" flat amp modules?

The parts may be an issue to find: active devices are

UP07 / UN07 (low power JFET - g*d knows what to replace them with)
2SK117 (findable, though the two Idss grades may be an issue)
2SK150 (dual N-channel JFET - another unobtainium part?)

So, forum, two questions for you all:

1) Do you vote yay or nay? Do you think it's a completely crazy idea to recreate what is a nearly 40-year-old design? All the (very few) reviews and comments I have found seem to indicate that the PRO was significantly better-sounding than the already pretty good CA-X.

2) Do you have any ideas WHAT to use for the blessed parts above?

Thanks in advance for any comments and responses!