Can J heads bee used with a roller cam?

You’ll need to clearance the pushrod hole. The shorter pushrod has a more severe angle. A die grinder and bit for the iron is needed.

The valve spring needed may take some work for use. The inner spring may interfere with the valve seal and the springs installed height can be an issue.

Comp Cams (and other places) sell valve seat cutters that narrow the seal area for different seals and lower the step as well as make the seat bigger which normally is tan issue with an OEM head because MoPar uses wide springs.