All I know is that the starter ring is located in a different spot on the flywheel. The rings have a different inner ID by a fair margin too. The old style oil pans located the centerline of the engagement. If it was a matter of shimming it out on an 8BA starter plate, it might be do-able. If it doesn't go far enough in to engage properly then thats a different story. Most folks just get the 8BA type flywheel to use the early type clutch to solve the problem of late to old but that won't help if you only have the old style flywheel to use.