TOPIC:

how much do i need to trim to increase the compression on my 440

the less milling you do on a head or cylinder you do,other than to clean up and straighten things the better.your cam chain tensioner will only take up so much slack before your cam chain will run loose and start chewing guides and gears up.you are also limited to what you can use these parts on after milling if you ever put differant pistons or cams in this motor .

As far as I know, the only way to get high compression pistons or hotter cams for a 440 is to have them custom made, so I don't think that will be a concern
I am not familiar with the 440 head so I can't tell you how much you can mill off, you will need to have someone actually look at the head and figure it out. It will however, involve milling slots in the camshaft sprockets to get the cam timing back in specs afer millimg.

IMHO, it would be best to pick up a used head to try this on, then you could do a little porting on it as well.