I'm having a lot of trouble with a song that's around 10 minutes long. I can't get it to sync at all in EOF and any time I adjust it I just run in to more problems. Was hoping to find some help on this and see what other people did in this situations. Thanks

It can be done, people have authored charts that are longer than that. The best thing I can suggest is to assume that nearly any song you want to work on will not be a single tempo all the way through and that you'll have to make corrections throughout. Starting with a relatively correct tempo will help. Moving the first beat marker to the first beat in the song will help. Using the waveform graph will definitely help in the process of clicking and dragging beat markers to compensate for tempo slips made by the musicians.

 

There are guides in the tutorials section that go over the process in detail, such as this:

http://customsforge.com/topic/22655-syncing-your-beat-map-with-editor-on-fire-eof/

 

There are some ways to try to automate the tempo mapping process. It's not usually perfect, but it can give you a decent start on many songs that are in a #/4 time signature:

http://customsforge.com/topic/2393-how-to-get-beat-map/

It's also very possible that the GP file is not a perfect bar for bar representation of the version of the song you are trying to "sync".  Some copy/pasting of parts (riffs/verses/choruses) may be required too.