340 J heads fs/ft 2.02 valve

Yup, I have seen J and U heads that look like a J on the spark plug hole but that was because the U was cut to look like a J when they drilled out the spark plug hole. Smogger heads are supposed to flow better than early heads (with the same porting) as they have a raised floor, and as noted, a better short turn radius. a sharp short turn causes a dead spot that hinders flow. And smogger heads all have hardened exhaust seats as a bonus.