US 220 (I-73/85, but should be changed to I-73(95), I-85(122),
Definitely not
I-85(122), as this is the only intersection with I-85.
The existing
I-73/85 doesn't quite fit, as this isn't a
highway jumps from one numbered multiplex to another sitution.
Keeping the existing
I-73(##) nomenclature going makes sense; i.e. I-73(95).
or even just plain 78 though going to US 220 exit numbers is probably not the best idea)
I think the less painful or potentially confusing option is to keep the grandfathered-in "US Routes don't
(have to) use exit numbers" approach.
Otherwise, changing would cause a big cascade of changes to other labels with a conversion to an Exit-numbered route.
I-73(94) -> 94(73), etc. etc. etc. A potential headache; there's been lots of confusion about the styles.
Be careful not to look down the abyss...It's up to mapmikey of course as NC's maintainer which option to take.
But of course I've gotta toss my opinion into the ring.