A Close Look at Speedmaster's Roller Rockers

How do you have your hold-downs? narrow-wide-narrow-wide-narrow? BTW, you can buy .010, .020, & .030" shims to give yourself .015" clearance per pair. I even think valve spring shims will work. Don't quote me on that though.
narrow-wide-narrow-wide-narrow, by the way where can I get these shims?