Making file permissions match

I'm working with some Windows programmers that don't believe in file
permissions They keep sending me zip files of their source tree.  I
have my copy of the tree in git on Linux with all of the correct file
permissions.

So I unzip the archive they send me and to see what they changed. I
unzip it on top of my git tree. But now all of the file permissions
don't match. The code deltas are there but there is also all of this
noise from the file permissions.

Is there an easy way to deal with this? I want to keep the code deltas
and ignore the permission changes. Since there are about 100K files
this is too much to do manually.

-- 
Jon Smirl
jonsmirl@gmail.com