What kind of base fuel pressure should I run on my return style setup?

Combo details:

2000 LS1
Texas Speed 224/228 cam
LS6 intake/TB
Holley fuel rails
Holley 66# injectors
03 Cobra fuel tank
Fore Innovations billet hat
Twin Walbro 255 pumps
8an feed line
6an return line
Aeromotive 13105 regulator
Holley EFI system

 

Stock is fixed at around 60psi.

But it's entirely up to you and what you need/want and the abilities of your fuel pumps.