hi
mines not the prettiest solution but it works very well for getting air out of the engine.
i think that keeping the header tank/ filler high and the ability to easily ensure that it is just coolant in the engine is far more important than the size of the header tank.
If you dont have a top hose with an outlet like mine you might be able to tap into your manifold to get at the coolant (this is what I did to mount the temp sensor near the thermostat).
LoBelly