Thanks for all the input. After a week of searching I have found some of the original crank bolts. I also include a photo of the bolt installed.
Having now measured up these bolts I am still a little curious about the design. The threaded holes i n the crankshaft are just over 1 inch deep, but the threaded portion of the bolt is only a half inch long. The diameter of the bolt just above the threaded portion shrinks down to less than a quarter inch. The hole through the gear is at least 20-25 thousands bigger than the diameter of the bolt passing through it. So there is no support against the gear if the bolt is stretch or strained, all of the gear alignment depends on the bolts being tight and being centered by the taper fit between the bolt and gear. Though it has the projecting flange in the back to keep it centered on the shaft.
I don't think it would be prudent to install used bolts in this repair, they have already had 50 plus years of stress and strain. It seems more prudent to install new, high grade bolts, even though that will mean either making them or modifying existing cap screws. Comments and thoughts please?