The spacer washers that S&S fit are about 2.5mm thick. I cannot see how your neat CAD profile will improve the ventilation over the washers. To achieve the current S&S style ventilation solution, Dremel or abrafile the slots in the front casing (as in Richards photo link) plus the cut out in the lower part of the cover. As you are doing all this it would be a good idea to do the modified crankshaft drive gear, bolt and idlers at the same time. That's an expensive cam belt, I hope it lasts a full 30,000 miles!
