If I remember correctly, you posted about your issues with sbs before, but then, you weren't actually reverse proxying your sbs server. You were connecting to it directly but thought you were reverse proxying.
You need to provide more details on your setup. Is sbs running on a separate machine? If so, sbs also running on port 443 is fine, it's a different machine, different ip. If le and sbs are running on the same machine, sharing the same ip and network interface, they cannot both run on port 443.