I like the idea of old in the new. A 440 and 727 in a newer Challenger is fine in my book. Save you thousands over doing up an original plus any collision shop can fix the modern Challenger. You'd have to eliminate all the modern electronics and wire up all your instrumentation with aftermarket gauges. would be a lot of work replacing new tech with old but not impossible. I spoke to a gent at the dragstrip in 2019 who had a 2015 Camaro with old skool carbureted small block and Turbo 350. Yes it was a drag only car but looked nice and he said it wouldn't be a stretch to make it street legal. The car was a stolen recovered insurance buy missing its engine and trans but the body was still like new. Said it was much less $$ to go this route than an actual pre 70 Camaro.