Is there a reason you don’t mention Anti Newton ring glass? My modified Durst 138 8x10 uses that quite successfully.

A source mentioned here or on the LF Forum is http://www.fpointinc.com/glass.htm.
I have no personal experience with them.

That site has some interesting links.

What are Newton Rings and the history of solving the problem.
http://fpointinc.com/history.htm

Cleaning your Anti Newton Ring Glass
http://fpointinc.com/cleaning.htm

John Powers