Can you port and polish a 5 cyl diesel head?
 

In the gas V8 world, if you port and polish your cylinder heads it's an instant 30-50 hp over stock, for example in my '98 32V 4.6L DOHC Lincoln Mark VIII, w/ported and polished heads I added 45 dyno verified horsepower.

Can I take cyl head off of my diesel, port and polish it and make some more power??

Most engines that are ported have RPM limits at 6,500 or higher. The diesel engine can muster around 4,800. Porting might pick up 5hp or a bit more but doubt that there would be any real improvrment. THERE is a company called Extrude hone that would do the head & intake and that might get you 10 more hp.