904 Pump Housing Leaking Between Ports

Hey guys, have a '76-78 904 that I'm rebuilding for my Duster. I have 5 clutch front clutch and pump (it's tapered on one end) Problem is that when air checking the clutches I have air and fluid leaking from the front clutch port to the rear clutch port. It's leaking at the pump split line halves. With 20psi I can actually actuate both clutches simultaneously. I assembled the pump halves by putting the pump in the transmission housing and torquing the bolts. I even did it twice and and tried lightly sanding any burrs on the surface where the two pump halves meet. Is my pump garbage or am I doing something wrong??