Unfortunately you should have the same head as mine which is the 0630, the 7120 head was only used from 91 to 95 models and even in the 91 to 95 models there was another head used also which i believe was a 7119. Anyone feel free to correct me if im wrong..

 

2 things. You can see the head number without removing the valve cover, and port matching is worth it but not necessarily all the polishing.

 

I don't understand... myself if I have it out I'm working the throats and bowls as well as ccing the head... worked well for me in the past.

 

I know what you're saying and I think it's probably a good idea. But for the average Joe running a 4.0 it's easy to just match port to gain a bit cuz the manifold and heads don't match well to begin with.

 

How about throwing a 4.7 in there? Is that possible?

 

I think the specs for the later HOs were more HP and more torque than the earlier HOs regardless of the head. IIRC, it was more of a function of the intake than the head.

Trying to swap back to OBDI would make for more headaches than gains.

Smaller ports on a mildly tuned engine aren't a bad thing. If the ports are too large you lose intake velocity and it hurts performance rather than improving it. If the power gains are only at higher rpms, its only of value on the race track.

 

Even a mild port job on these heads-bowl and throat and a gasket match does not make you lose much velocity. That's where experience and good blending comes in. You don't enlarge the port that much. More or less smooth the throat and streamline the valve boss. Also clean up the area around the valve and smooth the chamber. Also ccing the chambers will help it run much smoother.