Ditto on the mechanic.

If you have a 216 intake manifold, the carburetor mounting post-to-post distance is smaller than on later 235 intake manifolds.

http://www.classicparts.com/1947-53-Carburetor-Rebuilt-216/productinfo/81-021/#.U0KXj8dRG2c

http://www.classicparts.com/1947-59-Carburetor-Rebuilt-235-CI/productinfo/81-025/#.U0KXqcdRG2c