David,
I just received Midwest Photo's latest sales bulletin. They have a two 305 mm G Claron lenses in stock. The 8+ condition lens is listed at $429.00 and the 9+ condition lens is listed at $699.00.
These are supposedly really sharp lenses and have excellent coverage. I know that the 355 mm G Claron will cover 12X20 format. I am not sure, but it seems that the 305 mm was represented to cover 11X14. Perhaps someone else can verify that. The only condition is that this is a F9 lens. So it is slower and dimmer but I shoot a F9 Dagor on my Deardorf and I can certainly see to focus. Hope this helps, good luck.