Permatex "high tack" the red stuff in the spray can #99MA? That is good stuff for holding gaskets in place & works good with cork & is a spray adhesive & does seal very well but it is very thin & not made for gaps like RTV is & not saying I am a fan of RTV cuz I ain't. I wouldn't want to use RTV on cork (not a dealbreaker just a preference). "the right stuff" goes on like RTV but is far different & dries rock solid, just me I would not refer to it as RTV to avoid confusion as it is far better. I still think you have an excessive gap or poor fitment (including the cork gasket) somewhere. Good luck as leaks are just a pain to deal with as you know. Do check the "new" pan rails for flatness