Thanks for the replies.
I was able to seal up the base and it tested free of v. leaks. The idle came down to 1100rpm, no lower. I have had this carb apart three times. I simply can't determine how air is getting past the seated throttle plates. I can only assume that some internal passage that got drilled into, or that I am unaware of, is allowing v. through the carb. I can choke the engine out by covering the primary bores. The only access to the intake should be through the idle by-pass passage in the airhorn. But, the by-pass holes in the main body are plugged, so the air can't pass.
I believe that there is a problem with either the baseplate or the main body. Either way, it is beyond me. Thanks for all the help.
