Are you talking about a standard cover where the screws are seen through? Or solid chrome? I'd think any kind of cover would have to be fabricated specifically for that pickup, which was not designed for a cover. You might have luck contacting the Custom Shop to see if it could be done.
I have tried to get SD to make it but they won't. There is one way though.
go to a shop that mills thin sheets of brass or whatever, have them mill out a topper, add an open chrome cover, and done. will work just fine. SD just won't do it for reasons that are beyond me.
These might be the closest to what you are going to be able to get. Normal humbucker covers don't fit because the polepieces are in the wrong spot and the radius of the rail.