well i've spent a few hours today pulling apart the J head on the first quatro, and it looks like i'll probably be stripping the quill and putting a new bt30 atc spindle into it to replace the R8 spindle. It would be a shame not to utilise the existing head and quill with it's bearings.
The design of this spindle will probably be longer that the design on other ones, so mine may well be a special.