Rainman makes a good pump kit for Mags.
I have one and like it. I'd reccomend getting the Hittmann lever for it as well.
I used mine for a year without one then ordered it. I prefer with the Hittmann.
Your body and rail must also be milled for the pump kit if they are not already.
Rainman offers this service as well.
Link to his forum on MCB.
Kits are $150ish.