4-3 or 3-4 defenses.

With regard to those two defensive philosophies does it make a difference if you are stuck with a 4 man defensive front while also carrying a linebacker group that normally utilizes a 3-4 defensive scheme?
Ex. Philadelphia defensive line with Chicago linebackers.

No real advantage, but is there a penalty if you use a 3-4 and you don't have a lineman specifically eligible at NT? I think you take a ratings hit if you use a DT as a NT. Therefore I always use 4-3 unless I have a D-line like Buffalo that has NT eligible players.