See through valve covers?

mill the tops off some nasty M/T's and glue on some glass tops. PLexiglass may darken but the glass will stay clear and its not that much to get cut to shape. Just glue then on with silicone. put a dab of yellow paint on the rim of the lifters so you can see them move. Your going to have to look pretty deep to see the lifters. Good luck finding a clear cap.