I have a built TBI 454. I am using the GM vacuum referenced fuel pressure regulator. It holds 12psi of pressure at idle and jumps it to 18psi at WOT. The only problem I have is the ACDelco replacement fuel pump can't keep up with the engines fuel demand at WOT above 3000rpm.
I have used a JET FPR too but it basically sucked. Too rich or too lean...never just right...but it was still better then the stock FPR, which was ALWAYS too lean with the 454..
Chris