The prime reason Dodge went with the 6.2 (which is really a BGE block shared from the 392 with a 5.7 crank) is to maximize crank journal overlap, which adds a lot of inherent strength in the rod layout. A 6.4 or 5.7 boosted is not going to have this level of internal strength. Thus, you'll get people who say, "It's fine, I've had no problems," and others who will say, "Don't do it, mine blew up." With a piston/rod swap you can solve the 392's ring land issue, but you won't solve for the crank journal overlap.Thus, even the best built engine is going to be built with an architectural weakness.