The 'lead uppercut' from any sort of mid range distance is not a very smart move.
To do that would be asking for a clocking as you open while in his range and are too open the whole way through the action.

As a counter under one of his shots on your first move maybe a possibility, like if you were fast enough to allow him to dive right in and deal with his attack off your rear hand while moving out to his side and uppercut with your lead, cause you could load it on your move and land it on your landing in closer and out to the side of his attack, that takes some balls and some practice.
Or maybe as a second shot as you move in after blasting his arm out the way or making him react to one side; with a low hook uppercut combo off the same side as you move in on him could be another part of a fist move.