What the equivalent of May v Mac in a UFC fight ?

Lot of mma people, (those not stupid enough to think Conor will win at least), keep saying that Floyd would lose an mma fight to conor a lot more one-sided than this is going to be and so somehow Conor is still better. However Floyd going to mma to fight Mcgergor isn't the same as this fight in boxing for 2 main reasons. 1. Floyd is 40 and coming out of retirement while Conor is 28 and in his absolute prime. 2. Floyd is a defensive safety first fighter and Conor is a Ko guy so Floyd wouldn't have a punchers chance and a decision would be very unlikely for him in mma. So my question is what fight would be the same as this ? i dont know much about mma fighters but would it be something like a younger GGG v GSP ? and would the boxer have more or less chance than conor has in such a fight ?