The Latin RX7

So my s5 t2 one day started burning coolant at start up then cleared up when warmed up, so I ordered new coolant seals from mazda and opened the engine, turns out it was a damaged seal. Assembled the engine back and it did the same thing and after 2 more removal and installation of new seals its probably another thing causing the problem…if I let the car sit for a couple of days the engine burns coolant to the point where it fouls the front rotor spark plugs but no overheating whatsoever but anyway I have to open it again but this time Im going to do a full rebuild new housings new everything. Im asking my self though if I need new irons, heres a pic of the only thing that I see suspicious during inspection it looks like corrosion on the lower part of the front iron it is the only one that has some kind of visible damage any help will be appreciated