Milling 225 head

I really doubt the compression ratio was 8.2.........

You need to take measurements to determine what the actual compression ratio is currently............

If you were lucky, it might be high 7's! After taking the head off, measure how far down in the hole the pistons are. Then do the math to figure the current compression ration. I would deck the block first and then cut the head to get to the compression ratio you want. My block is decked 90 thou with a head clean-up at 10 thou. my compression ratio will be a little above 9.0