Hi Bryan,
1. The bushes sometimes have a slightly raised inner lip at one end, where they were parted off during manufacture. This needs taking off, I used a small deburring tool.
2. The pin is AN3, and should take an AN3 nut (all the bolts in the kit are AN, except perhaps the little ones in the trim linkage, and the big SS ones that hold the main undercarriage). I would look at the pin very closely to check there is no damage or weld spatter (since the pin is welded to a backing plate.) I would then try more than one nut, in case you have a damaged nut. If no nut/s would start, I would then clean up the tip of the pin, where the thread starts, with a fine file: once the nut is on, the thread at the tip does nothing.