Originally Posted by Chachi
Here's a site that might be helpful: Paintball Tech Ratsnest cocker tech
There's a drawing for an (old) stock WGP 4-way shaft. It might be beneficial to mill your own 4-way, and just use an existing shaft? That way, you could fit it just about anywhere. Just a thought...
Yes, I think this would be the best idea over buying a 2/3/4-way made according to arbitrary (related to your build) specs. Obviously it would require more work, but might not be more than you would think given you still have mount an aftermarket valve. Good point mentioning the AT lines. Even though I owned one year and years ago, I think you're absolutely right - the only auto-nelson (including pump assists) that doesn't seem to do serious damage to the gun's internals/valve system.
In terms of adding the three-way into your gun design, you might also want to look at the hardware/internals for PPS's quickswitch 3-way or whatever it's called. The seal mounts seem like they're be super easy to incorporate into your own design, modular I'd call them. This might be the same case with the wgp 3-way mentioned, so please forgive me it this is being repetitive.
EDIT: from one of the above links, this is what I was talking about regarding PPS's quickswitch