Yeah, I mostly agree. The biggest thing with the “swirl port” deal is that all kinds of people misapply that label anyway.
The guy that ported the 308’s for my 340 said the exhaust port floor looked better than some of the earlier heads. It wasn’t a huge difference but the 308’s did flow better on the exhaust side than the J’s.
It may come to that, but a simple cranking compression check will tell you some things without tearing all the stuff down first. Like Rusty said, we know the cam, we can ballpark the cranking compression to the static.
My 340 has a static compression at 9.8:1 and cranks between 175-180 on all cylinders
