Don't forget in classic there were two flavors to download depending on where the path to perl was located. Your version of classic may be the wrong one for your new server. You can open one cgi file and look at the very first line I believe.
If your path to perl is different and you don't have both versions you will probably need to edit every file in classic to change it.
There was also some test scripts included in the original zip to test what your paths are.
