Cummins HBI-600 specs

I have to replace the head gaskets on this engine, I have gone to the dealer and was told anyone with knowledge of these engines are either dead or retired. I am just looking for torque specs for this engine to get the job done. I believe it came out of a road truck from the 40's or 50's, no s/n that I can find. Any input on this would be great.

Cummins HBI-600 specs