If the FAA allows the Encore+ with FADEC, the V wing and ProLine21 to be the same time as the Citation I, then there's no reason whatsoever the CJ4 can't be the same type as the original CitationJet.
Same to be said about the common 757/767 type, A318-A321 type, and the 737 type...
That said, no predicting what the FAA will do and I guess we'll see...