I think that Lopez would beat him. Even the version that fought Quartey- eating jabs like popcorn but hurting Ike with every punch he landed. All 7 of them. I think it is possible that he could stop Forrest. It could turn out the Page fight where Lopez scored a knockdown with every punch he landed-3- but lost every other second of the fight.
At first I was agreeing with PR and siding with Forrest, but then I thought about it more and back Grey. I feel like Lopez at his best would catch Forrest late and stop him, while down on points, obviously.