Usually degreeing is only done on aftermarket cams, mainly because the lobes aren't always in line with the TDC mark. Obviously, different power gains at different RPM's and such can be had as well.
I've never read up on degreeing GSR cams, i suppose it could help but don't expect anything like an aftermarket cam would bring from fine tuning. You should see a small gain though (with tuning, and degreeing i could see maybe 5-7whp or so), i'd be impressed if you gained a decent amount.
Hit the dyno, find out, and post up the dyno charts when you're done :p