Afternoon all OK so I've taken the head off this /77 1500 spitfire engine, which CLAIMED to have had an unleaded conversion at some point. And looking at it im not too sure... I was expecting there to be some sort of small ledge or obvious difference in metal, however the valve chamfer seems to blend seamlessly into the face (see photo) Having had a damn good scrape inside the throat of the exhaust port, i find there is a bit of a ridge (see other photo), but what i don't know is, is this a normal part of the casting, or is this likely to be the back of where the seat has been pressed in? I don't want to moan to the seller until i am sure either way... Thanks!!