Twas I, Jib.
Burnishing was my "better idea', and I regret it greatly.
I no longer endorse burnishing. It has turned out to be a great embarrassment and loss for me, as the variations in pumps and their materials is too great. Some bodies are "chilled", and will only damage the burnisher, and chip the seat badly.
Upon developing different dressing tools, lapps, and burnishers, it became apparent that there was no way to accurately pilot off of the pump body cap threads, as they were quite often inconcentric with the seat.
Thus the only effective tool in my kit was a flat-bottomed stone, used to relieve the old seat to a sharp edge.
Upon bench testing with bubbles, it soon became obvious that was the best one can do, as any angle-grinds, burnishing, lapping, or even beating with a drift only made leakage worse, and occasionally did damage.
I would post pics, but the site's format will no longer accept my browser.