[fire85gslse]

ok reading the rb site a bit more. Their recommended FP is internally bypassed at 6psi and allows you to set you regulator at your setting.

looking at holley's site:

Fuel Pressure Regulators – Carbureted
Two Port 1-4 PSI, Chrome
PART #: 12-804
Fuel pressure Regulators are used to adjust for fuel pressure requirements of various carburetors. Too much fuel pressure for a given needle and seat assembly may cause flooding or driveability problems.
3/8" NPT Ports; Allows Adjustment of Fuel Pressure to Compensate For High Flow Fuel Pumps

Features
* 3/8" NPT ports
* .220" (7/32") restriction
* Low Pressure (1-4 PSI)






Again I would drop down to 3psi and try a few days at that to see if the starting issue goes away.
Seems you might be flooding it with too much pressure. It might be blowing past the needle and seat but not real sure on holley's