[FWB]

your original post. the 7 psi seems high. when i go to 7 with my dual holleys it over powers my needle and seat. i run a mallory electric 140 GPH.
the fact that you have the mechanical pump restricting the flow, and it will, is keeping the pressure at bay so the 7 psi probably is more like 6.5 at the carb.
in the last post you mentioned a 3/8 OD line.......too small for a motor like yours at high revs. switch the line to 1/2 OD, loose the mechanical pump, and drop fuel pressure to 6.5 or lower. you should then have no issues feeding your carb.
at the high revs you need to overcome inertia also and the 3/8 OD just can't provide the volume necessary


p.s. put the filter after the pump.....