For the Bass Casting Swivel Bell BC-8-A, is it possible to have just the 1/8’s one side and on the other the 1/4’s?

We're sorry Vince, but we don't make a 1/8 and 1/4 combination for Bass Casting - Swivel Sinkers and we do not do custom work. We do offer Blank Molds for custom design. Perhaps your local machine shop could mill one to your specifications.