And how do you think that would have fared? Mario Kindelan & Aleksei Tishchenko are my two picks. Arguably the best boxers on the planet in their primes, they'd have bagged a ton of belts between them if they turned over. Your turn...
Definitely Kindelan, as you said. The man was like a damn cat and actually got better as he got older. So relaxed in the ring. I don't know just how well he would have actually transferred to pro, though.