Need help, R3 vs Hemi, 6.1/6.4,,turbos??

Your 4 speed bell housing will bolt to a G3 Hemi. Top center bolt in BH not used though.

The way I look at is.....a built 340 with 400 true HP at the flywheel will sound like a built 340. Kinda radical and not good MPG on premium fuel.

A 5.7 Hemi with just a mild cam and headers is easily 400 +. And it sounds like an everyday modern Challenger. Bonus, it's lighter than a small block by 70 lbs or so.

Try that and if its not enough, you can turbo or supercharge later.