Those cams are very close. Did you check the 0.200" duration on the Hughes cam? Judging by the lobe lift (.395/.407), it should be within a couple degrees. My first guess is that the new cam is a tiny bit milder overall, but will idle worse. There is a chance it might handle the car's full exhaust system better than the straight pattern 108 Comp Cam.

If the car changes by more than 0.05 seconds (plus or minus) I will be surprised.