I went to Delphi's site and looked up specs on their pumps. Their vehicle look-up said FE0003 is the part number for my car. (78 Sunbird 305 cid) The operating pressure is N/A (edit: I found where it states: Relief Pressure 4.1-6.5 psi), and the flow rate is 23.9 grams a second. 23.9 x 60 secs x 60 minutes is 86040 grams an hour. 86040 grams converts to 189.685 pounds. Going on the high side of 6.5 lbs per gallon, this comes to 29.18 gallons an hour . Back to Delphi's site, their vehicle look-up didn't include 1976 Astre.
I found a bunch of automotive calculators here:
http://www.slowgt.com/Calc1.htm
and using the Fuel Pump Capacity Versus Horsepower calculator and reducing the hp a few times (using the default BSFC of .42) came up with 430 horsepower possible with this Delphi pump.
I could have screwed this up somewhere so don't take my word for it.