That does not coincide with other comments I have read from other well versed engine builders. How can you specify the compression ratio if you do not know what cam, or valves you are going to run. It is my understanding that slant six engines were quite varied in their actual compression ratios. Anyone wanting to rebuild one would need to know the target before handing the block and head off to the machine shop.

Sam

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Ditto what Sam said.

I would decide what grade of gas I want to run, regular, premium, race gas...and with that have a performance target,(HP, torque curve...) from the octane rating chosen, decide a compression ratio / cranking pressure, then develop a strategy for combustion chamber volume and intake closing - duration,( cam profile ) that got me to the performance target with the octane that I wanted to use.

I defense of Erson, they like Oregon Cam grinders have enough profiles to choose from that they could come up with a cam profile to fit the need.