I don't have a Duster but did the same front lip mod topside referred to, on my Plymouth B body.

I studied the way many of them were done.
The end observation was, as long as the lip is maintained, it will look pretty close to stock...even if it is relocated forward a couple inches.
When the lip is totally cut off as many race cars are, it isn't the appearance I was going for.
Not everyone would agree/no problem.

I might not need the clearance right now, but it opens up options for later.

Good luck with whatever you decide to do, even if it is to leave it alone.