Syncing Tempo to Out of Sync MIDI Recording?

Hello Friends,
 
Now, there ain't too much about dealing with MIDI timing, and recording MIDI that I don't know about after using Cakewalk since '88.  However, I can't think of any MIDI trick that I can pull out of my hat on this one.
 
I've got a piano part, that I'm using as a skeleton scratch track to build all of my other tracks on top of. And, as well played as it is, the engineer didn't even have the musical presence of mind to dial in the correct tempo into his Pro Logic project (which certainly says something about whether Apple users are so much smarter than PC users...but I digress), let alone have the player start on Beat 1.  Worse, it's obvious, he didn't even play the metronome while the player was recording so as to keep them playing IN tempo.
 
As I say, I know enough about MIDI that I was able to Slide the whole performance to where the 1st chord starts on Beat 1, where it's supposed to start, but when I play the performance back it's nowhere near the tempo that was set in the original project file. So, I've thought hard about any tricks I can use to push/shove it into a quantizable/manageable performance where I can build everything IN SYNC on top of this track, but I'm fresh out of ideas.
 
Any MIDI gurus out there, that might have any better ideas, or any ideas at all?
 
HEP ME!
KC