Be forewarned, I am no EFI expert. I had a similar build done a couple years ago (636 bhp). Dennis Quella had recommended we go with the Sniper 2 Terminator X. But by that point, those were backlogged, and my builder got a FAST EZ instead. Ultimately, we couldn't get it to work well for any length of time once we installed it in the car, it kept fouling O2 sensor and plugs, and the EZ is not laptop adjustable. I know at least one P-car owner using a better FAST model that has worked well, but with more adjustability. I know the Sniper 2 has a generally good reputation now. I also know a member on here who had one installed/tuned by a performance shop, who has had many of the same troubles my system had.
I decided to swap out to a Holley DP chokeless (I'm in NC so that can work) carb custom set up and tuned by Chuck Nuytten out of Rockwall, TX. He is well known for this, he will have you furnish all relevant engine specs and your performance/driving style needs and build accordingly. I have nothing but positive things to say about this carb so far. In my (generously long) phone conversation with Chuck on the front end, as I recall he said my issues were common and that the extremely limited O2 sensor placement option in Panteras can inherently create challenges. My point is, if you were going to spend the money to "upgrade" to a Sniper 2, Chuck is another option, for less cost, easier installation, easier parts availability in a pinch, etc. The only possible drawbacks I see would be some sacrifice of fuel economy, a little attention to the throttle on cold start, and a good mechanic friend of mine says Holley carbs can get sticky with periods of sitting unused.