Brace Height for Shakespeare Bow

[Old York]

Hello Everyone - I have an old (1964????) Shakespeare Wonderbow, Model X26-55. The AMO data is: 55", B51857m, 40 pounds at 28". I have gone to archeryarchives and gleaned  some  information, but...

1.) Can anyone verify the production year for this bow?

2.) Can anyone provide a brace height, and describe how one correctly applies this dimension? (Some people measure brace height from string to the belly, whereas some measure from string to deepest part of grip)

3.) Just what is the correct method for measuring brace height on older bows? I am speaking of bows which never had a berger button hole.

Any input would be most valuable - thank you!

Aim low!