Are you bracket racing?
Put a fan on the radiator. Consistent temps can and will help your overall consistency...and not just coolan temp. Oil temp and trans temp play a huge role (especially trans temp) in consistency. My stall speed at 120 deg is 5700. At 200 deg, it increases to 5900 give or take about 50 RPM (on the datalogger). Higher oil temp means slightly more HP due to less drag BUT too much oil temp is obviously not good. Gotta watch oil temp with alky-it will get up there but coolant temp can still be "ice cold". I've seen my oil temp get up around 220-240 with coolant temp stuck on 130.
I also have a front mount cell and belt pump. The only way to run alky, IMO. I also now idle on gas rather than on alky-which saves a TON of fuel and warms the engine in no time flat. Oil lasts all season too without changing it. Idles on 93 octane.
I also have an '84 coupe that used to run rear cell and alky carb. Fuel pressure always drops at the end of a run. A1000 pump. I'm at 1-2 psi at the 1000' finish line. Since it mostly ran 1/8 mile, I didn't worry with it too much. The cell feeds into a single 10an line, then to the pump, same 10an size line which runs up to the carb and to a home made log with a return style regulator on back (Mallory 4309, which BTW works GREAT for alky-hook the boost reference to the manifold vacuum fitting....1 psi at idle under vacuum and with no vacuum it goes up to 8-9) and an 8an back to the cell. I've since added a front mount cell and believe it or not, a holley black pump. Same 10 an line feeding the log, reg on back (after the carb) and a single 8an return. Pressure never drops unless there is vacuum on the regulator.
Friend of mine tried a BG400 in the rear, a similar setup as yours. Granted his was a pretty hot BBchevy (about 850 HP) but it never did feed the carb enough fuel. He switched to a front mount cell and the problem went away and consistency came back. Runs 5.62 all day long in almost any weather. He's got his game together. Too bad his health isn't good.
As far as running no radiator, that's best left for the aluminum block guys with dragsters that have plenty of air circulating around the engine. For those of us with cast iron blocks and/or concrete, because of the heat retention characteristics, it would be best to retain some sort of radiator, if for nothing else, to keep the coolant temp regulated. Or find yourself a billet block and forget about a cooling system altogether