This information is taken from a section of a Lycoming publication,section titled -Operating the direct drive, fixed pitch Lycoming engine The main purpose of this section is to inform you as to the proper rpm setting used to obtain 75% power at various altitudes.

In this section Lycoming uses a 180 hp 0-360 with a fixed pitch propeller as its source of information. Since the data is at 75% power the size of the engine doesn't matter. That is the rpm setting at each altitude will be the same for 150 hp- 160hp 0-320 as it is for the 180 hp 0-360, just the actual horse power changes.