So... What issues are a moderate Republican allowed to be conservative on?
Assuming they aren't a True Leftist, probably fiscal ones. People who are moderate on everything but foreign policy or social issues, tend to get tagged with the "neocon" or "fundie" label.
I think you're just missing the point here. Moderate isn't just being between the two empirical extremes. The moderate position on slavery isn't "some slavery."
Mark Warner is a moderate. Mary Landrieu is a moderate. If Mark Warner was a member of the Republican party, he would be a moderate Republican. Once upon a time, you had Nelson Rockefellers and Harold Stassen in the Republican Party. Now, you have only a handful of national Republicans that can lay claim to being moderate. If you're truly moderate today, you don't have a place in the Republican party.