So took the bar out and measured it with a bore gauge, 41.70. The finish is excellent, so hoping to get it to size without needing a ream. Hopefully finish it tomorrow
It fits. Line bored a thou over then thanks to Pete's suggestion of using a 3 legged cylinder hone, it was honed to size. It needed tapping in, but once rebuilt the hand wheel moves it very smoothly throughout the full range. Well happy.
No picture as I'm sure everyone knows what a tailstock looks like