Mamiya 645 screen options.

Hey guys.

I have a 645 Pro and I really want/need a checker screen, only they're incredibly hard to come by, apparently.
I've come across someone selling a checker screen for a 1000s, but the glass is within a differently shaped frame than what my Pro has.
The big question. Does anyone know if the glass within the frame is the same size, or 'close enough' to work? I don't mind a bit of elbow grease if I can get it to work (I'm starting to get desperate), but if it's just not going to work I'll have to hold out for the right thing to come along.

Any thoughts?

Cheers.

What is a checker screen? I have a few screens for my 645 Pro, but non are called a checker screen.

Checker/Grid/A4.

Ebay seemed to like the term 'checker' the most so I thought it was the preferred term.