Hi again,
Bolt diameter is relative to shroud load, not mast size. Same bolt size as clevis pin is a rule of thumb, unless there are two shrouds on one tang (like lowers). What do you mean by "double clevis hole"?
As for images, look through the ones here:
http://www.sailspar.co.uk/yacht-prod...ittings/tangs/.
Note that the tangs are independent of the backing.
Fair leads,
Brion Toss