Clarification on HP's comment: A Merlin valvebody will not remove the blowback from the system. A Merlin valvepin will, but you'll need to modify it for less surface area with a stock high-pressure valvebody, or your velocity will be really low.
If you go with a low pressure valve system, be prepared for a couple of issues that require quite a bit of testing to get the tuning right:
1) you'll need a HPR than can go to fairly low pressures consistently.
2) you'll be spending a lot of time getting the striker spring tension, spring length, and the HPR pressure balanced out, and trying to prevent burp and hammer slop. I tend to increase valve spring pressure by using a spacer, then cutting the stock spring down so it barely has any valve tension when the adjuster is all the way out, then drop the HPR to ~250psi as a starting point.
I usually wind up moving over to a custom spring that I source, but it depends on the valve type, striker style, etc. Usually takes quite a bit of trial and error to get it to shoot cleanly with no striker bounce, and no striker slop afterwards, but that's why people pay me to build and tune them for them...
--J