1970 Duster AlterKtion, 4 Link, LS/T56/Turbo and Minitub

Quick head math tells me you do not have enough pump. In parallel you will have plenty of pressure but it’s volume you are after at a given pressure. Those pumps have a maximum free flow rate of 70gph (roughly 264lph) and that’s free flow. In parallel at 53 psi you will not have enough volume.
Fuel Pumps and Horsepower – Aeromotive, Inc
Some worthwhile reading. Assume lower BSFC and higher HP and size accordingly.