fix timing for imported midi that is way off

I'm new to garage band. I've digitized old reel to reel footage I found of my father's original songs from the 60s. I've converted the mp3 files of piano playing to Midi via Klang.io site which did a pretty good job. When I import the 2 minute long midi files into garage band the timing of the entire piece is off (4/4 time has downbeats between measures and is not consistent. Is there an automated way to correct this? I can't figure out how to shorten all the notes of sections to fit to the 4/4 measures at the correct tempo. I don't think quantization can do this for timing that is off inconsistently for an entire song.

Thanks!

Using the current garage band software on a macstudio computer.