Cost vs. performance what do you think. My head is off and I have the chance to get it done if I want but I was just wondering if it makes much of a difference with these cars. Also, what can I expect to pay? I have a '86 951.

 

If you already have it off and are not in a hurry, do it. I think a shop I have gone to charges about $100 to clean up the head, but I had a lot of other work done as well. Also, it will depend on how far you want to go. Not sure on this engine specificly but on many others you can significantly increase the size of the exhaust ports.
If nothing else get a Dremel with some sanding drums and make sure all of the casting flaws are gone.