There may be an aeronautical reason for that toe in, but, it must be just another place the Phantom design was "bent to work"
Drawings of the F3H-G/H show 9 hardpoints, with no Rear ones, the two outer fuselage ones were parallel then, and had missile trapezes that deployed down before missile firing. They also were rated for bomb carriage. At the time, and the AH-1's time, there still was no area rule in the design, definitely not on the J-65 side yet. Looking at the bottom of your kit,,,,you'll see that the missiles will lay right along and parallel to the outside edge of the fuselage,,,,,,but just slightly wider apart at the rear
looks for all the world to me that in the course of their little, "bend up the aircraft" routine that Phantom went through,,,,,,the missile mounting was the first area "screwed up" by the requirements by keeping the front fins to the inside of the intake ducting, while trying to keep the rear fins to the outside of the ducting
our friend went through a lot at first,,,,,,,,,9 pylons on F3H-G/H, 11 pylons on AH-1, back to 9 stations on F4H-1, a nose that fit, then the bigger radar made the nose larger and drooped, inlet faring, replaced by a dozen splitter plate mods, nice clean wing and tail design,,,,,then, "bend this up, and bend this down",,,,all with a pair of engines larger than the original J-65's
Part of the fun of building these, though,,,,,,,,,they kept right on doing it to the design,,,,,,change the tail, change the flaps to slats, pin these flaps closed,,,,,,,change the main gear with two different "bump ideas",,,,,,RHAW, no RHAW,,,,gun and no gun
I think they did it just so model companies could sell more kits, though,,,,,knowing there'd be doofuses that would want to build each version,,,,,,,creating larges stashes of kits
Rex