i think it is kinda hard to do something like that, since GMAT gives you harder questions the more you get right and the paper diagnostic doesn't. Also, the GMAT algorithim weighs things differently.
For example, you and I could take the test, answer the exact same # of questions at the exact difficulty level correct, but get different scores. If we both got 10 questions of the same level wrong in Quant, but all my wrong answers were about circles, but your 10 wrong answers were about 5 different topics, you would receive a slightly higher score.
So I'd say if you got 'excellent' on all of the diagnostic sections you would score in the 700+ range.