750HP Craig The XFI system will work but have heard that any injector over 72 pound is very hard on the injector drivers over long periods on time. This way a couple of years ago. This is way I went with 55 pounds. My 482 motor only uses about 64% duty cycle at 6,200 rpm. You might want to rethink your system and go with 32-35 primarys and go 50-65 secondaries. Forget the map sensor and go alpha n programming using coolant sensor, TPS, O2 sensor, IAT. Map has problems with high lift camshafts and how wide the LSA is. The other thing is get a Snow injection system for water and washer fluid combined. You can have more timing, less gas wash down of the cylinder walls, cooler intake charge, and cheaper to use. It's a high pressure mister.
You need to do some home work with the 1/4 mile guys and find out who running what ECU. My dyno guy said that after my FAST system fails, he want to go to Moldex. Going on 10 years since the last failure which was my fault with a poor ground setup. I learned my leason on that one. If you have the money go doubles.
Rick L. Ps look at a TWM setup? I thought that they had a double injector bung hole setup for some motors??