The plans on Ebay are not a bad deal, but the price is hard to beat on the three view drawing in the link..
SR-71 fan often flies his 6xN20 motor B-36 around here. I think it has a one meter span or so.
Someone needs to get a little larger pile of foam and do a slightly larger B-36 for 6 GWS direct drive motors. A span of 50-54 inches would work, I bet. Or a 2 meter one for 6 Speed 280s, perhaps.