Man o man you are taxing the memory! Let's see how much I can pull out of the cobwebs.
1) I used two adapter fittings, one going into the master cylinder and for some reason I believe I ran a tap into it so I could use an o-ring boss hydraulic fitting as apposed to finding a metric adapter.
2) The other fitting is 1/8" male pipe X 3/8 I.F. adapter in 90 degree adapter.
3) The steel line is 3/16 that I bought at Autozone with 3/8 I.F. ends. I bent it by hand since there were no real tight bends and I had to cut it to fit and flare one end. I used a Harbor Freight double flare tool, it works but you have to go slow and make sure it works right.
4) I was a little misleading in where I cut the original cylinder, I pretty much cut the entire bore for the piston off. That little hole you are referring to caused me to re-think the entire operation but it ended up working out in the end. If I were to cross section it the adapter fitting I used (1/8" male pipe X 3/8 I.F.) and the banjo bolt share the same hole and come very close to touching.
5) On the wheel side id the stock rubber line with the built in provisions for the brake light switch.
So far it has work flawlessly, no leaks or any other issues. I have switched jobs since I made this setup and now work at a hose and fitting distributor. As I sit here typing this there is a fitting we have that could make the master cylinder transition much easier, I'll look into it tomorrow and let you know. I'm thinking one side could be tapped for the banjo bolt and the other could take the adapter.