chevy 230 inline 6 question

[67mater]

looking at buying this inline 230 from a 68 c10 which appears to be very original. my question is that above each exhaust port is a thread in fitting that has been cut off and folded over to shut them, and it has a shield/plate with a circle in it like a heat riser. I only see some 60s 230s with the fittings above the exhaust ports, and they are always capped. the date code ends in 7 suggesting it's a 1967 engine, but just want some confirmation or understanding what the fittings and heat plate were originally for. thanks!