What are these steam ports you mention? Is this an ls thing?
LS have them, but I don't think they are exclusively an LS thing.
The heads have 2 small holes on each end which is supposed to allow bubbles/steam to escape. On factory LS radiator there is dedicated inlet for the line from the ports, but I don't have an LS radiator.
I was thinking if the coolant got low because it was in the overflow, the radiator would draw it back, but it ain't happening (while running anyways). I bought a hose doodad with an NPT fitting that goes in the top hose and I will run the line there instead.