There`s no light heavy in history with a chin like Mercer`s, he took Morrison`s best shots and with a bigger ring a guy with Mercer`s reach would struggle with Lewis who peaked a couple of years after his fight with Mercer.
Believe me Michael Spinks would give tough fight but not by brawling. Maybe Bert Cooper or someone else?
Prime Cooper when he was active he could bang, he went full 12 with prime Mercer, I think he will do okay.
Bert Cooper was never a light heavy — his lowest recorded weight is 188 1/4 and there are only a couple of fights in his entire career where he scaled below 190. So I don’t see him in this discussion. In fact, the only two amateur fights listed on boxrec (obviously that’s an incomplete ledger as boxrec amateurs tend to only list major events like national tournaments and NYGG plus international competition including the Olympics) have Bert competing at heavyweight. If the question requires the opponent to weigh 175 or lower when he fights Lewis, the answer is no one. If the question is whether someone who had fought at light heavy and moved up to heavy could give Lennox a fight (not necessarily beating him), I’d start with Chris Byrd since his first two bouts were within light heavyweight parameters before he moved up. Lennox-Byrd wouldn’t be a Mercer type affair, but Chris could make Lewis look bad in spots and perhaps steal a few rounds, although I don’t see him pulling off a win. Michael Spinks and maybe Michael Moorer would have a chance to trouble Lewis in some ways but I don’t see either beating him.
I would clearly Favor Lewis over Qawi. But, if Qawi was in his prime at Light-Heavy, I suspect it would be far from a blowout. In fact, I think Qawi would give Lewis all kinds of trouble until he (likely) gets caught with something big and stopped late in the fight. I think Tunney and, perhaps, Spinks would do likewise.
That`s a long way to reach up without getting hit first and Qawi never faced an 84 inch reach, Lewis would have out-jabbed him from a distance.