Hello John – Sorry cannot help with your question but would like to tell you that I acquired a 3.5" Grayson many years ago and because I had access to a range of machine tools at the time was able to carry out a full re-condition. End result was a Grayson that was probably more accurate than when it was new. I found it to be a great little lathe and can still hear the slap of the leather drive belt from the wall mounted lay shaft.
Sadly it had to go (divorce). For the life of me and after some 30 odd years, I cannot remember what the tailstock looked like but I wish you well with the refurb., I'm sure you will not be disappointed with your "new" lathe.
ATB
Stuart