I can think of one downside - with a high compression head (and also other common mods like lightened flywheel, b carb etc) you wont be winning the slow driving car games like you would otherwise.
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Aaron in T̶a̶c̶o̶m̶a̶ Meridian, Idaho
(although still a Montana hillbilly at heart
)
1931 Coupe
1931 slant window sedan