I think Larry can outsmart Jim and send him to the canvas with a solid left hook to the liver.
Here’s how I see it: Lampley would be overconfident in his superior reach and stamina and would not train adequately for this fight. Merchant, with Big George in his corner, would outsmart his opponent by playing the rope-a-dope and make Jim get tired without landing anything signficant!

By the end of the 1st round both fighters will run out of gas (LOL) and keep fighting just on heart. By the 2nd round Lampley becomes increasingly desperate and keeps throwing more and more wild punches but Merchant just evades them, totally outclassing poor Jim. As Lampley gets out of his nerves and cries at Merchant, Larry realizes this is his chance and throws a stunning left hook to the liver sending Lampley instantly to the canvas. Referee Emmanuel Stewart reaches the count of ten and its over! Larry Merchant it’s the new HBO Heavweight World Champion!
Additional details:

Lampley’s Corner
Trainer = Roy Jones Jr.
Cutman = Harold Lederman

Merchant’s Corner
Trainer = Big George Foreman
Cutman = Ray Torres

Referee = Emmanuel Steward

Judges at ringside= Bert Sugar, Lennox Lewis, Ron Borges