Have you shopped for and priced G1 Hemi parts lately? I was offered a smokin' deal on a 392 block, and it was still double what I just paid for an entire 5.7 Hemi.
Have you looked at the weight of G1 parts compared to the G3?
As I noted earlier, DSR is selling 1150hp crate engines (My point being the power potential). Factory Stock Showdown cars are pumping out a heck of a lot more than that. Like 2000hp.
Dollar for dollar, the G1 Hemi will cost half again more or double what the G3 Hemi will cost, for the same power. And it will still weigh a lot more.
If I was to run Nitro (I would love to!!!), it would not be with a converter tranny, it would be with a clutch. I also probably would not use a 5.7 on Nitro. With me starting over with driving, I'm not going to trust myself with a clutch right off the bat. On top of that, Nitro and/or a clutch is not going to work in a car that I will have to run alone or with minimal help, or one that I plan to bracket race.