i dont like gasless welding to begin with, but thats my opinion. im a qualified welder, and have been for little more than 2 years, and again in my opinion, i dont think you should stick weld a manifold. yes, it will hold and seal, but it will look like crap if you dont have enough experiance with arc welding. tig is the way to go on a manifold.
the craftsman gasless is ok, if you just want to learn some of the basics. give it a shot.