Interesting! And rare!
The cooler itself is indeed the right part number for O-200's, but the mounting is different from shown in the ad when used directly on an O-200 (should bolt on where the screw-on filter El-Reno style adapter goes). One would need to replace the supplied adapter with Continental p/n 4763, forcing removal of their El-Reno filter adapter (I'd keep the filter). P/n 530264 does not appear in the C-150 IPC (p/n 4763 adapter does), but may have been available on special request as a factory option (uncertain).
This is not the same oil cooler found on all factory floatplane installations and offered as an option on landplanes, although both use p/n 4763 adapters and some of the same attaching parts. Either new installation would require field approval as a major mod to the engine's oil system.
