heres the block off plate i used for my cb350. i got it from chris marshall. it carries a seal for the crank, and screws to the cases. you do have to machine that joint in the cases flat for this to work, then use tiny town screws to hold the plate in. which means drilling and taping the case. it was all pretty easy to do, but would have been a total pain the ass with out a milling machine. the plate is flanged so it kinda finds the center on its own. which makes drilling the holes for the screws simple. anyway, i said id post pics. here they are.