There are two things about modern cars that I've found to be a hindrance to bracket racing: fly by wore throttle control and vacuum assisted brakes.

When I sold my racecar and decided to goof around at a Halloween event with my Crown Vic, the throttle response was so slow due to the electronics I had to leave on the 2nd yellow to cut a light. Flat on the floor for a full bulb before that 4.6 even came off idle. 4th round, needed to kill about .04 and when I swapped feet quickly, no brakes. Car didn't have enough time off WOT to build vacuum to assist with braking.

Fix those two issues (I'm honestly not even sure new Challengers use electronic throttle control), then it would as good as any car, even with the stock drivertrain. Next challenge is how difficult it is to see outta those things.

Also, if you're gonna swap transmissions and it's a dedicated racecar, a glide is King. Even the Drag Paks avoided 727s or 518s, they used TH400s.