my 418 with a ported victor doesn’t 60 much if any better than my 360 did with same cam, heads and headers and carb. 360 had airgap
going down the track you are spending virtually all your time between 3800 and 6000 rpm( again assuming non offset head and moderate cam…OP never stated)
in that range of rpm, dual plane with be more responsive, 4 inch crank or not.. I had more vert and gear and still had the result I had
this again all assumes it isn’t a light, cut up car. Mine isn’t, doesn’t appear the OP’s is either