Looking at getting at G0704 to CNC. The HF 44991 is more in my budget but the Y axis is too small. Does the G0704 ever go on sale?

I have looked at some extended Y axis info on the G0704 and getting more than 8" would be a real plus since a few things I want to do are 8" across. I have seen some claim just over 9" (which would be enough) and just ran across this that states 12". No real info though without signing up so I didn't do it.

Making a CNC Milling Machine - Increasing the travel - THE MAKERS GUIDE

I am guessing the 12", if possible, is not recommended due to poor support at the extremes?

My real question is about ball screw conversion. If I go for the extended Y axis (9+") do I need longer ball screws? If so, where can I get them? Or do I need to machine the ends myself for this?