You could call the new route I-995 (yes, I know that technically, I-995 would not be a spur, but I-540 in NC is not a spur, either, as far as I know). Or you could call it I-1095, America's first 4-di Interstate. Or you could call it I-301 (an orphan similar to I-238 out in California). Or I-101 (the East Coast analog to U.S. 101). Possibilities abound.
I’d steal I-97 and use that. The route would traverse 4 states. Another possibility would be to call the new route I-95E and the current route I-95W.