I have always believed in a 'high-volume' pump. Back in prehistoric times we had to make them. You took a good standard pump body and threw the insides away. Bought a rebuild kit for an FT pump. This gave you a taller gear and rotor. Press the drive out of the gear and load the pressed-out shaft from your previous set-up into the new gear to the same OA length. Hacksaw off the lip area of an old pump body to create an extra length of body that's a bit more than the extra height of the truck gear. Then take the ring thus created over to one of the valve body departments at T&C where they had the lapping operations for the valve bodies and put the ring in to make it flat and just the right thickness to make for an over-all pump body that fits the taller truck gear. When it's lapped flat and just the right thickness, ream the bolt holes in the ring to remove the threads and assemble the whole works along with the covers from two pumps, (for extra strength). Use longer bolts to get enough thread engagement.
Waa-Laa (voila), a longer, larger pump with greater capacity. (It's nice to have an Uncle Henry)---now you can buy a pump with the longer body and therefore greater volume.
KS