Death Korps of Krieg team question.

I know there is lots of information about this team how it's out of production etc but I came across the regular 40k box of them at my lgs with the intent of making a kill team before I did the reading. I know the suggestion is getting the actual KT box for the B sprue to make the special operatives and run a 14 group. Most of the information I came across mostly points to not being able to make a usable team from the 40k box.

Looking through it all and the variants on the back I'm a little confused why I couldn't just build and run Watchmaster, the 3 gunners that are included (melta, flamer and launcher), sniper, medic (proxy with the white bag) and 4 troopers? I'm not after meta builds, just a small group that plays friendly games.