If nobody even runs a 430 or 462 now when there are vast piles of them that get scrapped because can't be given away, so i think it's far fetched to believe theres any market.

Those engines will go bigger than that quite a bunch cheaper. Offset the crank and use 440 Mopar rods and you can have a cheap 500+" engine... getting bearings, gaskets, an intake and stuff is the next problem.