I think the answer is here:
https://groups.yahoo.com/neo/groups/bsa/conversations/topics/13582BSA service sheet No. 207, October 1948, re-printed May 1955.
Engine nos. XA7 - 101 to 600; first re-grind 1.4600 to 1.4595, with a
0.065/0.060 face radius both sides. No second re-grind.
Engine nos. XA7 601 upwards and A10 models; three re-grind possibilities.
1.4495 to 1.4500; then 1.4400 to 1.4395; then 1.4300 to 1.4295.
More information from that service sheet; Note that certain engines will be
found to have the left-hand connecting rod drilled to improve lubrication
......
BSA service sheet No. 207, October 1948, revised January 1958.
As above, but also data for the large journal crankshaft;
1.677/1.6765 with 0.120/0.115 face radius; 1.667/1.6665; and 1.657/1.6565
(10, 20 & 30 thou undersizes).