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.058 to .060 minimum clearance. check it with a dial indicator thru the spark plug hole.

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This is correct, the clearance needs to be measured vertically, the Super Stock Hemi builders do it this way.

While .055" radial clearance is more than is required and will undoubtedly 100% keep the piston from ever hitting the head in that plane, performance will not be optimum.

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Measuring with the indicator will give you the precise clearence of any part of the piston that is closest to the head.For most engines used for street and bracket racing a little extra clearence is good insurance against a catastrophic hic-cup.On any scienced out class race type engine the tighter the better.We used to get the dome as close as possible untill we saw shiney areas on the dome,but no contact marks.This was great for making power but put the engine close to "kill"with the slightest screw up.This can be quite costly.If you want a fast engine by all means tighten it up,if you want a dependable engine that will give you good performance and longitivity give it some extra.