Hello, I am just starting a leak down test and discovered leaks at the carb joint.  After I dissembled the block, I found a gasket between the joint and reed assembly that's not supposed to be there!  The diagram shows the only gasket is between the reed block and the cylinder.  I'll leave the gasket out, but is it OK to smear a light coat of sealant there just in case?  I see there are sealing ridges in the joint surface, but after 50 years, they may have flattened?  
Thanks All, 

I have been using a gasket there to avoid the mess of the sealant. The rubber is supposed to seal it, but the originals are all old and dried out, and the repros are not as good as we can hope. All 3 times I have pressure tested a bike they have leaked there without a gasket or sealant. Not once with an extra gasket. I have been coating those gaskets with the red Maxima assembly grease to help out future me.

Thank you!  I ended up using a thin coating of Permatex Motoseal and that did the trick.