Unless you are lucky enough to have one come with your engine, you are going to have to make a fitting to connect the SCAT tube to the carb.
I started out with a formed alum. flange and a 4"x4" piece of .063" sheet. I used a 3" hole saw for the opening. The hole pattern for the bolts are spaced at 3.25" center-to-center. The two parts were assembled with countersunk flush rivets. Sealant was used between the parts and when finished the flange was mounted using a cork gasket.
