Joe - I just went out to the shed to check and yes, the 2 skins are mirror image. I put the left skin on each side of the fuse, reversing it for the right side and the holes line up. The L and R skins are mirror image apart from the filler hole, and the joggle on the upper edge of the R which I assume fits over the L. Should be no problem to you to make the joggle. Will send pics if required to clarify.
I'm intrigued by your mod - please show us.
Cheers
Shirley