Seems reasonable. In all fairness Holyfield would be significantly larger than anyone Tunney had faced or Tunney himself. He's also fast, has very respectable power and has skills. Coming up in the same era I'd favor Tunney as a talent but h2h I have trouble seeing him deal comfortably with such a skilled big man. Holyfield wasn't really a small heavyweight IMO.
Tunney only lost one bout drew three times. You make a good point on the low weights though. It is tough to call. Tunney only losing one fight out of 84 with 3 draws. HGolyfield does have the weight advantage though.
I think they earlier, faster, harder working but a bit more vulnerable and less powerful Holyfield matches up better with Tunney than the one who beat Tyson. The latter i'd consider to be 50/50.