Good hunting, Richard,
You want part No. 42-4761 which has a kick leg or 42-4762 which doesn't.
They were used on the early A65s also.
The 68-4721 would most likely be from an A50/65.
I have been known to use B40 stands, which have the same leg casting, and widening them by replacing the centre tube.
Bugger of a job!
Trev.
