Mechanical fuel pumps

Hey guys! If anyone here running a mech. fuel pump with a 550+ HP smallblock, I'd sure like to know which one.

Have tried the Edelbrock, Holley HP, and both show a pressure drop at 5500RPM and above. Both drop to 4PSI or so.....

I ordered a Clay Smith pump and it's just too big! Hits the water pump bottom outlet, gotta send it back.

I'm tring like hell to find the Carter "strip" pump that needs a regulator, but nobody lists it anymore.

Also, although the pressure dropped on the dyno, the motor never went lean. But I just think I'm giving up some power with a pressure drop that low.

Sure hope you guys can point me in the right direction. This is getting frustrating!