Re: O2 sensor help...
 

Needing that much fuel pressure to get the A/F correct would say to me that the MAF function needs to be shifted to deliver more fuel. I'd expect that with the 331 since your pulsewidth (and load) is based on the factory displacement of 302 ci. I'll be interested in seeing how much power you make. I've got several customers with 331's similar to yours and typically they're in the neighborhood of 360 rwhp on our Mustang Dyno.