J/X Head exhaust flow?

“For what most people are doing with them”........ the factory 340/360 head exhaust ports aren’t a significant enough limitation to keep one from reaching their goals.

They aren’t great ports, with their poorly shaped floor after the SSR(aside from the 308 head), but there are other heads from the same era that are worse.

Generally, after the valve job is done.......the first well executed 5-10 minutes of work in a J/X head exhaust port is the best bang for the buck.
After that initial work, it takes a lot more time per/cfm.