Was just looking for this thread as I really wanted to get your views on this one @Xplosive. Turns out you were looking for other people's views and got none! I honestly don't know on this one. @George Crowcroft?
Johnson was the top contender in the division for at least a couple of years before he actually picked up a world strap at flyweight so I guess he could have got a shot at Arbachakov but once he had a title himself that probably would have made it a harder (though more attractive) fight to make. There was such a paucity of great unification matches in the 90s.
I think Too Sharp should be favored here as he was overall the more gifted and accomplished of the two. Arbachakov would be a very live underdog, and a Yuri win isn't out of the question, but I'd take Johnson by competitive yet clear UD.
I like Too Sharp here. I don't like how he's painted as a miniature Whitaker, though. He's more of a banger, an aggressive, imposing style with rapid hands, fluid combos, a big punch and debilitating bodywork. Yuri's textbook style is actually more aesthetically pleasing IMO, but I don't think he has the capability to shut down an offensive dynamo like Too Sharp at his peak. He could feed that cross down the centre, and try to ward Johnson off with the jab, but I think it's more likely that Johnson gets up close and really hammers that body. Yuri's defense relied a lot of reflexes and his weren't as good as they ought to be. They weren't particularly tested in real life, but they would've been vs Too Sharp. Johnson wins a decision IMO, possibly even stops him.
I wouldn't say a Too Sharp stoppage is out of the question, but I tried to give Arbachakov the benefit of the doubt as he had a solid chin. He could be hurt/dropped though, so a Johnson stoppage isn't impossible.