Macklin via KO1. I mean, look at the trouble Hearns gave Hagler. Macklin is a shorter, more compact version of Hearns. Mismatch is an understatement. :deal
The result would depend on WHERE the fight took place, Britain or the USA. You can never discount the importance of LOCATION in a fight like this. Because in Britain it would be 'murder' whereas in the US they'd call it 'homicide'.