milling my 906's heads .080

My 440 flat top slugs are down in the hole. I would like to increase my compression 1 point I have read where guy's have milled there 906 heads .100 and shaved a 1 second of there 1/4 mile times. I would like to go .080 and of course mill the intake side also
I was going to buy 440 Source heads and have them milled but my buddy told me I can have the iron heads milled for about $200--cheap, Have them checked for cracks first.
ANY OPINIONS OR ADVICE WOULD BE APPRECIATED
I am running a mechanical purple stick 559 and need to get my compression up a bit 160 or so

thanks