Gary and I have always had good luck with the 600hp Precision core. Nice cast end tanks with smooth transitions, garrett core, mounting bosses. I would recommend that and have Gary make you some IC piping. Other than that I personally wouldn’t use anything else as this is tried and true. Your horsepower goal is reasonable on the 16g a little high on the 400 side with 93 octane. Meth is a band aid. If you want an honest 400 awhp get a 30R 
Good luck