You will actually gain a little power at 60 over, due to slightly more displacement and more compression pressure, but it would take a skilled dyno operator and a fair amount of luck to actually measure it. Be sure your cooling system is up to dissipating the extra heat load the thinner cylinder walls will create. Installing a new water pump and a new or rebuilt radiator would be a really good idea.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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