I have emailed NASA National that I am agreeable to separating Cup & Spec into separate run groups, and I know Dave Derecola has as well. If the option of runing with GTS-1 also exists, I would choose that, as I prefer NASA passing rules to Cup passing rules, among a few other minor issues. I received an email back from JWL that he would do his best to make this all happen for us, and he had forwarded our wishes to Ryan Flaherty, who is doing the run groupings. I do not have anything definitive on this yet, though.
Spec Cars have been competitive in Cup, though this is partially because only Jersey Joe has brought a Cup car built to the limit of the rules so far. Last year, my Lap times were 2nd fastest in Cup at Nationals, doing nothing but bolting on a set of 16" wheels with Hankooks, adding 50lbs of ballast, and adjusting my rear antisway bar. My lack of experience/racecraft, landed me in 4th place, after having caught the second place car with two laps to go:(. With an LSD, real antiway bars, and no weight penalty (due to changes in Cup rules) my car should be more competitive, and hopefully the driver, too.
Spec ran with GTS-1 last year, and to my knowledge, I finished ahead of those guys, so we can be competitive there as well, at least until someone maximizes the GTS-1 ruleset.
With trackside support, moving between Spec & Cup/GTS setups is very doable. VFC made that happen for me last year, and I'm sure Mantissport could as well. You could either take out ballast to get to 2530 (if the car is light enough) or add on Hoosiers/Hankooks/Khumos +/- DME to make the car faster in Cup/ GTS-1. I think tires are worth more than 70lbs, but more expensive than weight.