E body leaves can be moved in an inch to allow 335 tires and still retain the splayed layout. However, to mount a similar 335 up front will require some massaging of the wheel openings. Not out of the realm of possibility, but a slightly narrower tire for a square set up may be preferable. Since this is a track only car, a 275-305 slick would be great. If you want to go with a 305-315 UHP 200tw tire, that would also work.

I believe the 71+ B bodies also have a splayed leaf layout, but I think it is reversed from the E body and is wider in front. I don't have my chassis book available to confirm. A bodies and pre 71 B all have parallel leafs. This isn't a huge detriment to performance, but was part of the reason that later models were more refined in their feel.

If you just want an open track day car and ultimate performance and wheel to wheel racing is not necessary, any of them would work. Any of them will get a lot of attention. If you think body damage is a risk, then the Chargers and E bodies will have the most readily available panels in a wider range of materials. Personally, the open track days I have been to are for predominately street cars, so they make pretty big efforts to preserve the integrity of everyone's equipment.

Weight is a factor in performance as well as reliability. The lightest of the bunch would be preferable for that.

NASA offers time trials classes where you could actually race your combo against the clock in classes factored for modifications. This would certainly expose you to competition factors without the potential for wheel to wheel contact.

If you think actual wheel to wheel racing would ever appeal to you, then NASA's American Iron or Camaro/Mustang Challenge, which is focused on pony cars, could be an evolution of the car. In which case, you would want to start with an E body.