I just purchased a 383 hp challenger that is in excellent condition. However, it is a factory auto on column. Will it be a crime to put a 4spd in it or do I leave it as original? The engine is year correct not orginal motor. I welcome comments.

Go for it!

(just keep the parts you remove)

Don't waste your time with a 4 spd, go with a 5 or 6 spd OD...

All according to your money supply.The cheapest is stock 4 speed, then up is the 4 speed OD, the the 5, and 6 speeds are next, but those require a load of cash. And if you go with the off brand 5 or 6 speed you will need a machine shop, and welding shop. Look in your bank account before you start.
Now a cheaper way to make it look good is to put a slap stick, and console in it, and keep the auto.

It will increase the fun factory and curb appeal and probably the overall value. If it were a survivor I would have a different opinion but non numbers 383 column auto Challenger, no blood no foul.