Hi Paradox, I was just in for a cup of tea & saw your reply, I planned on loading to the 7x57 specs and working up a load.
The bolt handle is the original , Marc Newton from Rigby very kindly supplied me with the info on the rifle and their records show the bolt as a "Flat lever " , I presume as this was a Best rifle , the customer would have ordered it that way .
I have worked out how to regulate the sights , I ordered a reproduction catalogue and it describes how to regulate the rifle with adjusting the front sight.
Regards
BJ