I'm not sure you're going to find one that fits.
The only SLC-500 controller that has an 8-pin Mini-DIN connector is the SLC-5/04, and that's keyed and pinned for Data Highway Plus.
If you're trying to have a universal connector for both SLC-500 and MicroLogix controllers, you're better off using DB9 than the 8-pin Mini-DIN that's on the MicroLogix itself. Those are keyed and pinned differently than the connector for the SLC-5/04 DH+ port.
I've never seen a comparable DH+ style Mini-DIN connector available in a bulkhead style. Even Grace Engineering, the market leader in PLC-specific bulkhead connectors, doesn't offer one that I can find.