Reese, Welcome to the forum.
I wonder what makes the mechanic conclude that you have "a wrong pressure plate"? It sounds like a guess rather than a diagnosis. Sometimes the throw-out fork can actually be bent. I'd examine that first.
When you write that it takes "a great deal of leg strength", are you saying that it's hard to press over the entire range or that it doesn't disengage until the pedal is at the floor? If the latter, then the bent fork diagnosis is looking better. Conversely, if its difficult to press over the whole range, then there could be a clog somewhere in the hydraulics. Something might have been dislodged during the clutch job, and it is now clogging a port somwhere....(THAT is just a guess!)
On their death bed, nobody ever said, "Gee I wish I'd spent more time at work!"
'68 Sprite 1275
'76 Midget 1500