As an unhelpful aside, while you are carrying out detailed and complete measurements of bed wear, I suggest you check other components, ie, various lead-screws and their nuts, cross and top slide for rocking and lifting, all the various oilite bearings including countershaft etc. etc…
Only sayin cos if the bed is badly worn, then everything else is usually well shagged also. Then your small project suddenly becomes a bottomless money pit as well (wonder how I found out?).
Secondly, if you are considering a second hand bed, you gotta ask the question why is it for sale? I would suggest it is extremely unlikely that you will find one in an unworn condition.
Edited By Martin of Wick on 04/01/2022 10:14:50