If I come across one, I’ll let you know.
Not the best, but better than nothing...
http://www.cnn.com/ELECTION/2008/primaries/results/scorecard/#val=R (you can click the RNC Unpledged tab or select other graphs from dropdowns)
http://en.wikipedia.org/wiki/Republican_Party_%28United_States%29_presidential_primaries%2C_2008 (Scroll down to breakdown)