Did you look at the Optima D31 yellow top? I have it as my backup battery and I'm sure it meets all the requirements. It's big but I'm sure it will fit (mainly a height issue.) I may or may not have to extend the cables but I'll use another one as my main replacement if I can.
Optima batteries are good, but the group size is different. I wanted something that would bolt right in without any modifications to either the battery hold-down or cables.