The venturi suction controls the fuel flow rate through the main jet. There probably isn't much difference in volumetric efficiency between the side valve and OHV engines (though there is a big difference in scavenging efficiency and compression ratio, that does not affect venturi suction) so from that point of view venturi suction would be similar and calibration should be within reason. However you said the Kohler is a twin cylinder, and you didn't say what engine the ebay carburetor is for. The difference in pulsation in the venturi between single and multiple cylinders does have an effect on the mixture, especially the emulsifier calibration. It isn't a major difference, but it could potentially be noticeable.
