A tough get but Ishii would be a fantastic fit for it tbh.It could also be someone else from NJPW. Maybe someone in the midcard.
It is kinda hard to find someone better than PAC in the indies. A lot of people say Moxley, but he is not a better wrestler. More known and a better promo yes, but wrestling wise he is bellow PAC and, according to Melzer, it is someone better than PAC.