They did put 360s in some that year, last year for it actually.
Having a 3.9 (also last year for that) makes it easy too as far as bolting everything together. Better than a 4.7 any day. If you're going carbed I'd look for a 500/518 "RH" series to go in behind that 318, or better yet add the 3rd pedal and the shifter ..