those headers in the pic have a floating 2bolt flange and a maleball conector, wich couples with a matching femaleball fitting, wich is basicly a flare that fits that maleball nothing special any muffler shop can do those, only downside i can think of with that is that it may not be optimum for flow but that can be solved welding in a straigh piece of pipe inside the colector..
betwen head and manifold is a good place to have a gasket, many cars came stock without but things happen when many years pass and cast iron heats up and cools down many times and it may not be as flatt as it whas 30+years ago thats when a gasket comes into the picture
