Hellcat and 6.4's have same 4.09 bore I thought. I doubt a N/A build is capable of finding the limits of any of the stock Gen 3 blocks. If big inch N/A is the goal then a 6.4 car or truck block starts out with the biggest bore without spending a boat load. Im unsure if the truck blocks have oil squirters like the 6.4 SRT and Hellcat blocks do and when a stroker crank is used they usually get blocked anyway.