That could work- the only difference between Buff and Light/B&W Columian is the latter has Silver.
I do not recommend anything feather legged. There are several genes for leg feathering and they also have variable expression which means a bird with the gene can show anything from lots of visible to apparently no visible feathers however it does have it genetically.. certainly something that can be a problem for generations!
How about Columbian Rocks? Actually it is possible there is already Columbian in the Orp stock, would not be surprised if it was in Buff, as an modifier gene to help create the clean buff body(Co is pretty good at clearing up "off" color on the body). Perhaps crossing the different Orp colors can tease out a bird with visible Columbian pattern..