I ordered reed valve blockoff plates (a.k.a. 'coasters') from Cruiser Customizing (P/N BA-2571-00).
Here is the front reed valve...
...and the rear valve. There's not a lot of space to get to them. I took my time with an 8mm wrench and eventually I had them off.
Here are the hoses and air valve that are removed with the reed valves. There is also a vaccuum port to plug.
Here is a blockoff plate in place. It cleans up the motor some.