Richard, (Rickity)
Head bolts are:- Long, waisted - 3", original bolt- 13/16" thread, pattern- 1" thread.
Medium, waisted, 2-5/8', original- 7/8" thread, pattern- 1" thread.
Short, plain shank, 1-5/8", original- 11/16" thread, pattern- 1-1/16" thread.
We shall see if Richard L's measurements are the same.
I suppose it's a matter of time before they call you "wrinkly".
Trev.