FWIW, I was running the mallory 140 in the coronet with the old motor making 550 hp or so.
With the new motor doing 770 on the dyno, Brian was concerned that the 140 wouldn't be enough pump.

I called RobbMC (before opening his business he was a design engineer at mallory) and he confirmed the 140 would be marginal at best at my new power level.
Mallory lists it as for 600 hp max (600-700 with a return style regulator), and he said they do build a safety factor into their published numbers.

They list the 250 as the recommended pump for 700-1200 hp applications.
So, the car now has a mallory 250 in it.

Based on your et's, you're makng around the same or better hp than I am, so I'm going to say the 140 just isn't enough pump.