I just picked up a 4.0 head off a 91 cherokee for the head swap and when I got home I noticed that all the triangular water jackets were already plugged.

Is there any reason to plug these on a 4.0? I know you have to when its going on a 258 short block, but I know for a fact it was on a 4.0

http://home.off-road.com/~cj5/ports.jpg

Looks like buildup from rust and hard water to me.

The lower hole in the picture seems to only be partially plugged