Yup, that'll work; but I don't think I'd bother if they're 9" brakes- but the 10' may already have the extra hole.
I think Rumblefish and I are on the same page- if I understand correctly he said he used B body brakes on his Dr. Diff axle swap- which is exactly right. But in order for you to use your stock small bolt axles in a cut down B body housing, you'll need A body brakes. We're just talking about two different setups.
