Sharkey, just remember that this LSX 454 is a small block, bored and stroked. It's not the ultra-cool old school Big Block 454, there would never be enough room in the JK's engine bay :icon_crazy: As far as street legal, that may differ from state to state. Throwing codes is a thing of the past, you just end up running what is basically two seperate computers; one (GM) for only engine, one (Mopar) for the rest of the vehicle. Not overheating is just not skimping on a radiator, go bigger.
Realistically, the 6.1L/6.4L Hemi is pretty badass too, and anything over 400hp like these offer stock is more than enough. I surely wouldn't turn one down if it was a low mileage junkyard pulled motor.