My point!!!!
I don't see where you're finding a 0.622 group in any of these
three parts books, which are the only ones I have access to:
http://chevy.oldcarmanualproject.com/parts/1929_41/index.html
http://chevy.oldcarmanualproject.com/parts/1929_54/index.htm
http://chevy.oldcarmanualproject.com/1929_57chevyparts/index.htm

None of which makes any difference to me since my 1959, 261
didn't have a slinger/thrower/ring behind the balancer and I
don't see any reference to one for that engine in any parts
books or service manuals.
dg

Denny G
Sandwich, IL