Roy Jones Jr doesn't have a prayer against Tyson at Heavyweight, not even the '96 version. Fighting a slow, plodding John Ruiz is a farcry away from battling a hard hitting compact brute like Tyson. Silly match-up, Jones would never get in the ring with such a man, and I for one wouldn't blame him. He'd last longer than Spinks did, but only 'cus '96 Tyson is faded at best.
Roy would need to have a perfect fight plan and follow it perfectly to win. But would only have a 2-5% chnace of winning this fight.