Once the hole was the right size for the wire, I found out that the terminal end of the insulator had to be enlarged also. It seems that although the terminal would slide in to the correct depth (there is an internal lip that the terminal seats against), there was not enough room for the terminal end to open up so that it could snap over the spark plug tip. Out came the die grinder with a solid carbide grinding tip, and I opened up the terminal end where the snap ring portion of the terminal is located. Opening it up to .375" was enough to get the spark plug to snap solidly onto the terminal. You may be able to see in the picture a mark on the carbide bit that I used as a depth reference. I didn't want to go too deep and hit the internal lip that the terminal seats against.
After all of the "machine work" was done, it was time for assembly. I used all Taylor wire products including their 8mm Spiro-Pro wire, straight terminals, and crimper.
After all terminals were finished, and I snapped one on a spark plug, I noticed that the insulator would "rattle around" on the plug. This was because of the fairly large gap between the I.D. of the insulator and the plug insulator.
I wanted a nice snug fit on these things, just like on modern plug wire boots that grip the plug insulator. I ended up making my own silicone insert. I first put some silicone grease liberally over the spark plug insulator and inserted it in the terminal, squeezed in a lot of black RTV silicone around the plug, and let cure. After curing, I removed the plug, trimmed the RTV, and now have a "modern" ceramic Hemi spark plug boot. It holds the plug nice and firm with no rattle. This was a big job, but I'm glad I did it.