Solo PCM's in Florida can sell you a PCM with the correct things disabled for a reasonable price. They are who I used, but I also had the ECM reflashed for more performance several times as I made upgrades from a stock motor to a stroked motor with ported Eddie heads and bigger cam. This required the purchase of a hand held tuner and a remote tuning service, which was not inexpensive. It was definitely worth it for me though, as it made a major performance difference even on the stock motor.
My ECM used 4 O2 sensors including 2 pre-cat and 2 post cat. I am using an O2 signal generator on the post cat feeds to avoid codes. I am running the pre-cat O2 sensors though, which is kind of the point of running modern EFI, the self tuning feature.