Technical GM flathead 6 engines

Hi everyone

I'm wondering if there are someone out there who cold give me some guidance regarding head milling for GM flat head SIX engines in general and more specific for the Oldsmobile BIG SIX 257 engine?

I came across a blurry picture from some sort of shop manual showing a table with recommendations for the amount of material that could be removed for different heads. Unfortunate the numbers was not readable.

Thanks in advance!

 

Are you wondering how much you can remove to increase compression?

or something else?

 

Generally with a flathead of any make, you want to minimize the amount of material removed from the deck surface of the cylinder head. Remove too much material and the head starts shrouding the valves and your intake and exhaust flow goes in the crapper. I would take off the minimum amount to true the head up. If you want higher compression, look at new pistons which would probably have to be custom any ways, so no additional cost there.