case sc 1952 flywheel bolts stripped

Trying to find the flywheel bolts part # 08530AB it a 7/16-20 bolt interference fit. Bolt Diameter is.435 same as an aircraft bolt or Hiloc. I followed the specs in the Manual it says torque flywheel 50 foot pounds the book is WRONG stripped at least 3. I thought the bolt was turning in the crank others are probably no good been over stretched. It should be closer to 36 ft lb when I checked the torque by bolt size. Has anyone had this issue before. Anyway I need to find a place to get 6 replacement bolts and nuts. New used whatever any help would be appreciated. A little input would be helpful as well. Heres a link to the bolts
Thanks Byron

http://partstore.caseih.com/us/parts-search.html#epc::mr66945ar131481

Any Aircraft guys out there what Nas bolt can I sub for this or is there a better sub 14 dia bolt grip length is 13

I'd be concerned about the butt end of the crank, the bolts will be harder than the crankshaft, really take a good look at those
internal threads................

(quoted from post at 14:38:26 10/10/16) I'd be concerned about the butt end of the crank, the bolts will be harder than the crankshaft, really take a good look at those
internal threads................

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This particular one has no threads in the crankshaft a special bolt that has the reduced head height and in addition The head radius that is were the shank meets the head and about .070 is milled off the bolt I assume this to be a 50s Solution to allow it to sit flush and true after driven into the interference fit hole in the crank shaft, this is a typical concern on bolt installation on aircraft and an Obvious concern for case Engineers of the time Period. I maybe able to over come this by installing a steel washer as a radius block under the head although there's not much room between the bearing carrier and the crank. If not possible I will be adding a chamfer (small countersink) to the back side of the crank this is called a fillet-relief and will allow the bolt head to sit flush & true it takes up the head & shank radius and allows for a clean install with no gap under the head. Truth is there's nothing special about this bolt with the exception of the diameter and shank length. no threads should remain inside the holes. This install was designed to not allow the holes in the crank and flywheel to get elongated and create a vibration. My Personal Opinion. I'm sure some will say I'm crazy but I will take no chance with this tractor that may create an issue if I can afford to do it as it was designed its worked fine for over 60 years. Everyone has to weigh out the consequence of not replacing some parts or substituting some as we all don't have unlimited Resources. In this case the new bolts are inexpensive and insurance that I will not be buying a new crank.