i have owned three 406 ci....1st one made 611hp 11:1 Compression
2nd one 13:1 compresison pair of 750's..made 700 hp range.. ( pushing it but no issues)
3rd one and still own it..460hp...10:1 static compression...fixing to put a 142 b&m blower on it at 5/6 lbs of boost and run some 110 octane..looking for 550hp maybe a tad more ( street driven)
as rabiddawg said the webbin is weak in these 400 blocks...i personally would not recommend over 600hp range without hardblocking it..otherwise i would run it and not worry at all.
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "