Maybe YOUR AMC engines are done revving by 5000, but that's only because you like slow, evidently. The Am V8 will easily rev 6500~7000 if you let it. Way more HP up there, maybe another 200 w/o ruining lowend tq entirely. A tradeoff.

As far as FI goes, I'd not overlook other makers units too. Like LT-1, LSX, Ford & Mopar OEM castings that may be adaptable to a Torker or Performer for the low rev guys. The UR-11 is a multi part casting that a top of a TPI, Ramjet 502, etc. may be adaptable to.

I don't know what would be so hard about cutting 8 pieces of rectangular aluminum tubing (intake port sized ID) and welding them to 2 flat aluminum plates that match & are bolted to the heads of a mockup motor. Then a flat plate to cover the lifter bay. Then drill & tap for direct port injectors to spray on the center of the intake valve, stem being used to split the squirt into a "Y". Then, we need 8 small throttle bodies, likely already in production. Possibly a pair of race 4 cylinder throttle body sets? If I could weld aluminum, I believe I could fab it up myself. For controlling injectors, I'm sure some aftermarket system can be used. Not opposed to mechanical system, either. Kinsler, etc. have been doing it for decades. Guys???