Porting J heads ?

If you haven't ported a few, then the best bet is to avoid trying to max them out. You can get good numbers with limited work around the spots that can be thin. You should also be familiar with identifying a core-shifted head. They're common and will affect the thicknesses. Stay away from reprofiling the short turn, be careful around the sides of the guides in the bowl areas. You cannot raise the roof too far without going through.