Need more pictures to be sure, but it looks like it could be a Poseidon to me. They use a mixture of proprietary parts and Bauer parts. I can not recommend an older one, since some of the proprietary parts are just not readily available or excessively expensive. I spent quite a bit of time working on one just to have it eat up a cylinder that I have not been able to find. Do yourself a favor and go with a straight Bauer block instead. Based on the HP of the Motor, I would be kind of skeptical to think it will put out 7.5 cfm. Its probably along the lines of a Poseidon p135 which is under 5 cfm. If so it is more like the older Bauer Capitano, and some of the valve parts are interchangeable.
Good luck!!
Cheers, Walt