Thanks very much for the suggestion, Dan! The Ilex shutter seems like a very accessible approach; maybe I'll see if I can find one without aperture blades for cheap (once the lens arrives and I have a chance to measure, of course).
I'm not too worried about the prospective coverage limitations---if it vignettes on 8x10, I'll either use the vignetting as a force for good or put it in my 5x7 kit. I've got a Gundlach Radar Ext. WA in a similar focal length and it'll be interesting to compare the two: a poor man's Dagor-vs.-Protar comparison, I guess!