Buy "The Book" on Q-jets and OverDrive Transmission Swaps. On the Website Home Page!
If you feel you need to resurface the check ball seat, try this: Take a small broken drill bit and epoxy a check ball to the end of it. Put a dab of fine valve grinding paste to the ball and give it a few spins on the seat. Make sure you spray/blow out the paste when done. Works well for me....