Pete, glad you were able to pick up the 300. I did the same thing with the windshield too. I've learned to just take them off when you haul them on a open trailer or truck bed.
I have 2 of the '76 400's with the 340/22 reed valve CDI engines. They are a very peppy machine which makes them fun to ride. Niether have speedos but I'd guess real close to 60 on a good flat. They run hard enough that the windsheilds want to lay back at that speed. Only trouble I've ever had is a CDI box failure on one of them.