Here is a quick-and-dirty web page that shows the intake manifold with 1/2" NPT hole (same GM part number as yours). Also shown are various fittings that I have accumulated (they are not for sale) and some images of fittings that would work with the wiper vacuum hose.
Make sure the hole in your manifold is 1/2" NPT (it most likely is).
NAPA and Grainger should have the brass fittings (or, be able to get them).
If you have a fitting in your manifold, you might be able to find a brass barb hose adapter for your vacuum hose.
