I bought a rebuild kit from Mikes Carbs.
http://www.carburetor-parts.com/4100...tor_c_171.html
In my case I had a 4100 1.12 version on an A code 289. Ran but too much carb and plugs were sooty. Had trouble getting a good seal on the sides between spacer and manifold. As others have stated only an 1/8 of metal on the spacer. I was tempted to silicone the darn thing. Ended up switching to an edelbrock intake and carb.