The Klitschkos in the mid 80's- mid 90's?

How would of the klitschkos done if they were around in the mid 80's to mid 90s? They would of had the likes of the great larry holmes, The machine that was mike tyson, frank bruno, witherspoon, bonecrusher smith, tony tucker, the real deal holyfield, bowe, old big george foreman, moorer and mercer and a young lennox lewis. Could they have delt with this much bigger range of talent and competition that they havent had in the 2000-present? Who would they of defeated and not defeated?