Done about 3 of these now.
One thing to be aware of whoever does it needs access to a decent sized mill as on the WM18 the bed sags in the middle underneath.
This happens in the casting process and is no problem except that it will not clear the ballnut. Remedy is to take a skim from end to end underneath, to get the clearance. WM16's may just clear, some do, some don't. Short bed WM14's are usually OK.