Modded several Master System 2's before like this one. I always used to follow other guides pretty strictly so I used an MD1 style 8-pin din socket as was the common way to do it. Never really thought about why. Eventually I wondered - surely just putting a SCART connector in there would be better, right? No need to buy an expensive MD SCART lead or make yet another cable.
Here's how it turned out. Red, Green, Blue, Composite via 220uF caps & 75ohm resistors. C-Sync via 220uF cap and audio via 10uF.
I started this mod a while ago and had to leave it because I had a problem with the Master System I was using. I eventually got round to swapping the board and picked up where I left off (hence the change in the following pictures). Also, it took me a while to figure out exactly how I was going to have this all wired up so some other changes were made after this picture was taken.
Finished version. Just need to stick/glue the board down.
...and from the back:
