Add an accelerator pump on a vacuum secondary carb?
That would be tricky ;-) If jetting up the secondaries, adding a power valve, or changing that plate didn't work, I'd go back to a double pumper. Maybe not the one you had, of course. There are options.
But if I had a warmed up small block with good flowing heads and everything else that took advantage of the improved flow (cam, intake, headers, etc), I'd be looking at a double pumper anyway. Call me a drag racer too
but your engine guy wasn't wrong.
1969 Mach-1 Mustang
460 / C6 / 9"
Back in Dixie DSO 22 (Charlotte)