Re: HellCat or Whipple?
Tuning is ok as far as the engine goes. There is nothing you can do as far as tuning for the transmission currently.
As others have pointed out, your price gap between trade and MSRP of the HC is going to be greater than your hypothetical.
If you do go the FI modded route, by all means forge the bottom end. From my experience I would say do the valvetrain as well. Reasonable estimate is going to be 15-20k - of course it can wiggle either way depending on what you do yourself/what you have others do/what 'others' you choose to use. If you do that, your engine is set up for more power than the HC will make. The transmission is going to be a question depending on how hard you push it and how much power you ultimately end up at.
2014 Max Steel GC SRT, built by the bad boys at JNAP
Livernois built 392 and Whipple Kit