From another thread. 6 MP camera cropped to 5 MP blown up to 20x30 inch canvas, and looks great. People spend way too much time sweating the small stuff. The stuff the technical guys say you can't do, rarely have much truth to them.
If you ask the technical guys can you take a 2570 pixel wide image print it 20 inches by 30 inches and have it look sharp, they'll say no. Yet, it's on my wall, as taken by my 6 MP Opito 80W and it looks sharp.
SO don't listen to the guys who say it' won't or it can't, listen to the guys who've done what you want to do and figure out how to make it work for you. Most of the time folks who say, this won't work or that won't work, if they haven't tried it, they're probably wrong. It's pretty much guaranteed that any FF lens will give you more resolution on a K-1 as it will on a K-3. Probably about 25-35% more based on approximate Nikon D810 numbers.
But will your pictures look better? No one knows, but based on printing my 5 MP image large, I doubt it. 36 MP is oodles of overkill for landscape.