How hard is if to swap a 1971 or 1972 dart front end on 1973 dodge dart sport

One more question... what is the front spoiler is that on the front end? Thanks for all the great info, definitely changing out that front end. Like night and day

It’s an OER spoiler for a ‘67 Camaro.

CHEVROLET CAMARO OER 3916673 OER Injection-Molded Front Spoilers | Summit Racing

It’s not a perfect fit but because it’s ABS it works fine. A heat gun makes it easier but it’s not necessary. The 68/69 spoilers work too, they’re a bit wider but not as tall. I liked the taller ‘67 version. For $30 it’s hard to go wrong.