I was looking at the Gen III hemi swap forum earlier today. VVT lifters coming apart, valve seats coming dislodged, Oy Vey. A regular occurrence no less.
Depends on the year of the engine. Best bet, get a 6.1L Hemi with no VVT or MDS and grab a stock 425 HP and 420 lb-ft torque out of the box.
And use a 42 RL transmission which gives OD without the need for an electronic control module and requires minimal tranny tunnel modification to fit in an A body. Put 3.55 gears behind it and it will be a perfect beast...for daily driving or doing 12 sec passes at the track.