Ben,
I just went to the Industrial Hobbies website. It appears that Aaron Moss found a buyer for his business so, they will be selling his version of the RF45.
HTML Code:
http://industrialhobbies.com/
I think this might be just what you are looking for. Also the IndustrialHobbies website has a lot of info on CNC conversions of the RF45 class machine.
Also search for some of the RF45 conversions and look at the bridgeport machines. On the east coast you can sometimes find a real buy on a used bridgepost on eBay.
Most people recommend that you avoid a round column machine for CNC conversions (especially if you don't already have it). So that would argue against the G1126.
The G3102 and 3103 only have 6" Y-axis travel, so they wouldn't seem to meet your specs either.
In the Grizzly line you would have to go with something like the G6760 to find something that would meet your specs without modification, which with freight is a little over $3000.
Alan