Bolt dims

I think they are just standard grade 8 bolts, I don't think that they have a flat washer, I used a find thread bolt and a nylon lock nut. As for the shoulder length. Do you have a caliper?
Measure the thickness for the steering arm, the bracket and dust shield, if you are using one. That is your bolt shoulder length, It should be a little short that the total thickness of the combined lengths. This is for compression.