Couple things I see, 1 is the larger diameter knurl appears to be engaging the block, is it binding and causing the bolt to stop turning. 2. The end 3 threads appear to be packing dirt/oil/crap into the hole and may be stopping the bolt from turning. I "think" the outer starter hole is machine all the way thru and could be tapped further, if the threads stop short. I would run a tap into the block and see if it will clean out junk in a couple threads and allow the bolt to go in further. I would, also, test that larger knurl to see if it is causing a bind and file it down to fit. If all that comes out good, but the bolt still stops short, you can cut 3/8" off the bolt and still have plenty of thread to hold the starter.

Mitch,

Thanks for the suggestions. I ran a tap through and cleaned the threads with brake clean. I found the issue, just didn't look closely enough the first time. When I put the correct knurled bolt in, it shifted the starter slightly inward toward the oil pan rail. The relief cut into the starter mounting flange that was supposed to clear the oil pan rail was not enough once the starter shifted over that small amount. I took it off, filed it, and it went right on. To test the proper engagement of the knurl in the block, I was able to use one washer under the head of the bolt and that was enough to compensate for that section of 10mm knurling that protruded past the starter mounting flange. I have access to a tool and die shop here at work so I will have them turn a small section off the knurling on the bolt and I should be good to go.

I drove the car through the neighborhood yesterday, and I have to adjust the clutch some more as the engagement point is too close to the floor pan. It's getting close to being back on the road now!

Good to see you are making progress. Extending the rod to the fork 1/4" will raise the pedal engagement point off the floor. Free play at the top should still be 1-2 inch, but I always adjust mine to a comfortable engagement at the bottom.