I am glad to see your restoration coming along. Sorry I have not been on here but today is the first time I have caught up on reading these posts since returning from vacation. Ron, John and JPG seem to have the help you needed well in hand.
For the Miter, the spring can be replaced by finding one that fits. Just not to soft of a spring and could be cut to length if a longer one is found. The pin is the difficult replacement. If anyone wanted to make some I'm sure they would sell. I would buy one for the extra Miter I have that is missing it. As has been suggested Miters come up for sale often but generally complete ones. There were only two Miter versions that came with the Model 10's. Yours is the second and most common one.
The Tailstock Bolt comes up for sale once in awhile. You can use, as suggested, a regular bolt plus a washer, in the mean time. You could try contacting ebay sellers that regularly sell Shopsmith parts to see if they have one. Do get the one shown in Ron's pictures which does not block the Extension Table from being lowered all the way down.
No worries. Hopefully you had a good vacation! Others on the forum have been great responding to my never ending list of questions as you can see. As for the missing miter parts, I'm thinking of trying a spring and steel ball combo like what I found in my spare craftsman miter. It shouldn't be that hard to find them in 1/4" D.
Contact ebay seller for bolt - Done!