On the money, ^ and if for the head you're going to bolt on to your engine,Tom is the guy to have do it. for that old head and bench, you could use it for experimentation. for a long time, the lemmings in the market bought into extrude honing ports as the end all be all of porting --an abrasive removal process that had no real guidance to what was being removed but to hog out the port all around. in some instances it does work, but not in the majority. A good head porter knows what to remove, what to leave alone and how much to take out. a little slip of the grinder and a lot of money can go down the toilet real fast. Remember to test at valve lift numbers that match the cam profile rates in order to achieve something that matches your goal as Tom alluded to above.
If i had a bench and wanted to DIY for my own engine it with no prior experience, I'd get some epoxy and port, test, rebuild the walls, port again etc. over and over til i find what works and would probably spend months and months doing it.
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