RJ,

Please take this in the intended spirit, no offense meant, but I think you may be indulging in false economy here. I, a couple of years ago, had a head job done locally that included blasting, chemical cleaning, flattening, hardened valve seats, and grinding the valves (the guides needed no work), and the whole job was $100 plus change. The hardened valve seat part of that job was $50. I may be wrong, but I would hazard that, allowing for regional differences and inflation, you could get a head job done for less than $200 and save yourself a lot of uncertainty and extra cost later. I pride myself on being as tightwadded as any ;-), but I wouldn't put an unknown red-block head on any engine without, at least, having hardened seats installed and the valves ground. If I were living off the grime on the bottom of the barrel and absolutely had no alternative but to put a head with unhardened seats back on, contrary to the advice posted here by others, I wouldn't lap the valves. There is a rumor about that some valve seat hardening was done at the time the heads were manufactured, or that years of running on leaded gas left some deposits or changed the molecular structure of the cast iron of the seats (or something like that beyond my range of understanding), and that lapping the valves would remove whatever is providing some minimal but, nevertheless, beneficial protection against valve seat recession. That may all be pure poppycock, but if the valves show no burn evidence, the seats look intact, and the valves appear to be seating well, I'd leave them alone. Before I swapped in a B20 for my blown-rings B18 with unhardened valve seats I added lead substitute and realized that, over a year's driving, I was spending as much on that as hardening the seats would have cost.

Bob S.
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"62 PV544 (B20, M41), "71 142E, "93 240 Classic Wagon.