While I on a roll, here's a little something some of you might find of interest.
The valve in the picture has 138,000 miles on it. The Ford 460 exhaust seats are so hard, the valve took a beating and the seats still look like new.
The valves all look alike and were replaced with Inconel exhaust valves $$$$. The valve guides were still with in tolerances and didn't need replacing.
One of the reasons I like Fords was the quality of the cast iron. Really tough.
The cylinder bores has less than 0.0015" of taper.
I've been using Walmart's Super Tech 10W30 Full Synthetic oil for the last 75,000 miles. So it can't be too bad. Hmmmmmmmmmmm

Richard