I've decided I'm going to put in a modern Gen 3 Hemi into my Challenger. My question is, do I go for the 6.4 or the 7.0? It seems like there are many more parts available for the 6.4, unless parts for the 6.4 and 7.0 are largely interchangeable. Is this the case? If I later decide to buy a supercharger, if it's made for the 6.4 will it fit on the 7.0? Will both of these run on pump 93 octane?