Yeah, there's a thread over in Electric Guns where I've been tracking my progress working on it...
And thanks to the input of
@Adolf Hamster,
@Asomodai and
@ak2m4 I've actually got it up-and-running.
I've not actually used the new piston and piston head, I got a better air seal with the old piston!
It's now running a teeny-tiny bit too hot at ~355fps so when I take it apart again to do a lube job with some proper grease, I'll maybe swap over (it's definitely better made, so worth using), see how it goes