Mark Levinson ML-1 power supply

I recently purchased some vintage audio gear at an estate sale auction. One piece of gear was a Mark Levinson ML-1 solid state preamp, which dates from approximately '77 to '80. Unfortunately, the external power supply was not included. Thus far, I've been unable to find a replacement online. I'm hoping something eventually pops up on eBay. In the meantime, I'm thinking of building a quality power supply so that I can actually make use of the preamp until I find the real deal online.

I have experience with a soldering iron building speakers and can follow (though not design) a schematic. I've never dealt with power supplies before and don't know the first thing about them. Mark Levinson tells me that the power supply was plus or minus 15V, 500mA each rail. They weren't sure of the pin configuration, and the connector is a bit of a mystery as well.

Any suggestions or insights on where to start would be greatly appreciated. Thank you very much.