Atco runs

Glad to hear you had fun.
Try lowering the float a hair maybe and if your running one of those drop base of even stock air cleaners switch it for something that doesn't create a sweltering cave around the carb. maybe raise the air cleaner?

Another reason I block the heat crossover with a piece of thin metal.

If you ran 15.19 then adjusting + the timing will possibly raise the trap speed, but could create more tire spin and slow you down.
Of corse if you get rid of the pizza cutters and bring the psi to 25 on real tires, then 15 flat should be feasible I think [with the current configuration].
Your tires + gears and you'll be a tire spinning .......you know what I mean.

A 3.73-3.91 gear and 2200-2400 converter would be nice in that setup.
I might also set the primary rods on the lean side for OTL 1/4 wot

Oh and if you get a holley you'll be in the 12's [joke]