I think I still have a couple or three in a carton that I missed when I sold my 8x10" gear some thirty years ago. These were well used when I got them, so they are pretty ancient, but they were light tight, though certainly not "very good/mint."
If you are anywhere near the Boston, MA, area, you could come by and I'll give them to you. They might at least let you try out your beast until you can find some "very good/new" ones.
I'll see if I can find them and I'll send you a PM. Where are you located?
-Eric