ugly it up and enlarge the belly putting in a shallow bomb bay. Fuel storage on wing pylons instead.
JCF, I was hoping you'd weigh in as the turbofan idea passed through my mind about 4 this morning.
GTX, how about increasing the sweep of the wing with a 10-12" increase at the root and a 5-6" decrease at the tip? One with, one without a dog tooth. And, fwiw, I'm anxiously awaiting Revell/Monogram's rerelease of the F-4C/D so I can backdate one to a similar aircraft to the F3H-H but with some Demon traits and some Daryl-isms tossed in.
Ron Cline, the guy who made the Allison-engined P-51D named Joker on Hyperscale, sent me a full T.O. for the Phantom some years back and I've been itching to do a number of Phantoms with the spurious one leading the project off.
Cliffy B, for your Brit Demons, how about a Spey since the J-79 fits?