Hi Jim.....
A few F-4 Phantoms flying out there with Jett power
Best engine suggestion is the "standard" version SJ-90L.
Sames "61" size engine block - similar to the OS 61/91 in size and mounting.
It is a big, draggy plane - and although quick, it will not let a 90LX version engine really unwind where it likes to.
SJ-90L, 12x6 APC. And you will be good to go
Bob