Non-relevant fact: Back in the early '70s there were kits you could buy to convert smallblock chevy heads from straight plug to angle plug. It involved inserting a cast iron plug into the straight plug hole and then drilling a new hole at an angle. I cant remember if it had jigs or instructions for a Bridgeport.

Relevant fact: Most 915 heads came with smaller exhaust valves. Only the HP engine heads were supposed to get the larger exhaust valves. Some of the HP heads had the letters "HP" stamped on the end of the head.

Possibly relevant fact: To the best of my knowledge the first B/RB heads to use the smaller "peanut" plug were certain of the 213 "motorhome" heads that were used on motorhome engines and had extra cooling around the plug. I do not believe that these plugs were angled. They were called peanut because they used a 5/8" socket and tapered seat and the plug body wasn't much bigger than a peanut.

There were also 213 heads that had no extra cooling and used the regular plugs. I have a pair from a 2-barrel Newport.

Chrysler wasn't building collector vehicles, they were trying to stay afloat by shipping product. The phrase "never say never" applies. That's what makes this wing of the car hobby so much fun.

R.