I have a few clean legged golden cuckoo marans....and some lovely fat black orps......
Marans would be an easy cross to do, since they have white skin like Orps do. It would be even easier because they don't have feathered shanks! A Golden Cuckoo Orp would be very pretty!
I thought about outcrossing to Wheaten Marans when I was thinking of making Wheaten/Blue Wheaten Orps, I just don't have enough space or tolerance from my neighbors to have that many boys around for a project of that undertaking though.