The Dooley on my big block Chevy uses a factory truck pan and uses an OEM type pick up. I run the pick up 3/8" off the bottom and seems to work great. I have also welded a bracket to it that goes to one of the tray bolts/studs, just for a little added strength.
From What I am told, Dooley made so many variations of their pan that it gets convoluted. I guess run whatever you feel comfortable with. I have seen Moroso and Hamburger pick ups used with the Dooley pan in some of the race boats, the Moroso just seemed smallish to me, as does the Dooley.
GT