No way is Tyson stopping Douglas of the Tokyo fight in one. This is completely over rating '88 Tyson. Remember, Tyson never fought such a confident guy who really fought back like that. Tyson isn't walking over him like he did to a "lame duck" Spinks.
Yeah, I THINK Tyson catches him and keeps down this time. However, if the odds were the same as their actual fight and I am soley armed with the knowledge of what happened in the parallel world of reality I am betting Douglas! If Jame Tillis and Bonecrusher Smith can go the distance with Tyson I am thinking that the Haley's Comet version Douglas would be at least capable of extending him!
'88 Tyson stops '90 Douglas. When, I'm not sure, but stop him he would, at some point. Hell, even the worst version of Tyson ever (other than the 2000s version) almost stopped him.