I use the Melling (Select) #10554
for almost all street rebuilds - both stock and performance.
For performance usually the only mod I do is to install the "white" GM spring to increase upper end pressure @10lbs.
There is no reason to increase the volume in a street driven small block
and lots of reasons NOT to
This same pump is sold under many companies names as their "Performance" unit
This pump has the high strength base and will not crack at the mounting like the weaker stock and M55 types.
Stock ... #10554
Also weld the pickup (usually stock GM) to the pump for added protection.
To get the location correct;
* remove the stock pressure spring from the pump
* mount the pump to block
* lightly insert pick-up into pump, with it slightly angled away from block, with a few slight taps - just to hold it
* set pan on block rail, without a gasket so that it contacts the pick-up and push down on pan to set pick-up to pan depth
* remove pan and tap the pick-up down an additional @1/4" from position pan pushed it to
* finish tapping/driving the pick-up into the pump to fully seat it against pump
* unbolt the pump cover (4 bolts) and remove
* weld/braze the pick-up to the cover (off the pump) [note: I use my MIG and a small weld to do this - I used to braze, but think it builds more heat in the part than the MIG weld does from a test with a IR Heat-gun - so I weld only now.]
* cool the assembly
* install the original or the new 'white' GM pressure spring
* reassembly cover to pump and finish build
hope this helps;