I had an original pro flow. It indeed had a fuel pump that mounted to the frame. The old Holley pro jection, was the same way. I just bought a Fitech, it has 3 options, in tank, #1 option, their canister with your stock pump # 2 option, and frame mounted that they say will work, but they recommend in tank. Tech said it was the most reliable, and safest.
1969 x-77 Z/28 orange/ white stripes, named by my daughter "Clementine ", M-22 close ratio, 4:10 12 bolt, CE 302. Hugger orange with white stripes. White standard interior. Restoration complete May 2018