Spinks would never see the sixth rd. He'd be beaten like Cobb was, but wouldn't be able to go for too long
Spinks would always have given Holmes problems. Styles make fights,but a prime Holmes would catch up with Spinks by the ninth or tenth and stop him.
Prime Holmes would be too much for Spinks and would stop him around the 7th or 8th round. Spinks' resume as a HW is mediocre at best and it didn't have on it a prime Holmes. The only quality HW that Spinks fought in his prime flattened him and Holmes would do the same...Just a little later in the fight.