Chris,
I had my 428SCJ bored .065 and have never had a problem with it. It was sonic tested before and after the bore, then blue printed and balanced. I have ran 11:1 compression in mine since I got the Cobra in 1969. Only problem and I cured that was that on our 110+ humid days it wanted to run around 235/240 degrees. Both of my engines normaly run around 210 and that is what the engine builders told me they should run. I mounted one of thos e spray type units that they used to use on the old trucks so I can just push a button when the temp gets to high and it sprays a shot of cold water across the front of the radiator. A couple of quick shots will lowet the tmep by around 10/15 degrees for a while.
Ron
