Don't know if anyone has tried this, but it seems to have worked. Before I knew the difference, I bought a K1 airbox for my newly acquired K0, on eBay, for not much money. ($20 bucks I think) Then I stared at it for a year cursing myself. But I'm not sure if I was being cheap, or just wanting to not have to order one from far away, so I wondered If I could grind off the ridges. I seems like it worked, granted, it's not really correct, but I'm not really going for a concours resto, so, I'm fine with it. It turned out pretty good I think. Ground off the ridges, used some Bondo type stuff for plastic car fenders to smooth it out, and painted. What do you think? Here's the before, middle and after shots.