I believe that the Maddman Rocket valve
for "The One" will work. It has no blowback port.
I advise you to buy a rebuild kit along with the valve. Since you have to file down the pin every time you screw in the "SRP", it's nice to have a spare in case you go too far. I wish I'd done this on my Spyder clone.
Honestly, the Type R valve tooks to be pretty darn good as-is, but I'd be curious to hear what upgrades do.
As for the stock parts, the bullet cupseals from Alamo City Paintball
will probably fit, and ought to give a little better flow compared to the stock seal.
Please post anything you find that's interesting to the thread in my sig.