If he is not in a hurry, you could place it on a flash drive and express mail it to him.
As for resolution, well here is a print guide to help you decide.The Print Guide: Image resolution for printing - LPI vs DPI a.k.a. LPI vs PPI a.k.a. LPI vs SPI
220 ppi is the lowest you should go while 360 ppi is best.
Or a DVD. People managed huge files before the internet...
With a image that size, you can go lower in resolution. I print a lot of 30X40 posters and use 150 dpi, as the printer they provided me at work would fail if I used a higher resolution. If you're having problems with your computer handling the large file due to many layers, try creating different files for some of the different layers that can then be flattened and used in another file to keep the file size down - don't try and do it all in one file.
Thanks a lot for your insight guys, it was really helpful!