So I'm in the middle of plumbing and on the drain holes on my the acrylic plate I have it is made for 1.25" plumbing so I'm getting 1.25" bulkheads. Do I get the bulk heads where the PVC should screw into it on the top and the bottom ? Or slip? I'm coming down from the 2 drains then I go to a union, then I go to a gate valve and into the drain plate, but not sure if I want to remove those pipes what to do? Thank you~