East RC is going to release a 50% Cassutt soon:
http://www.eastrc.org/shop.cgi/page=...39113891.30879
Other than that I don't know of any in your desired size range. RCM does have several versions of the plans for smaller planes, perhaps one could scale up? The biggest plan is # 780 with a 41" wingspan.
http://www.rcmmagazine.com/store/sto...dwrY3YwiY656S5
You might also ask Dick Hanson on this forum. He is a big fan of the Cassutt and has been working (on and off) on a design for a few years. He doesn't do plans, but he may be able to give you some direction. Send him an email.
If you build one, you should do a build thread!