There is no problem blocking the aperture of the lens to be at the wide open position when mounted on the K-1. All you need is a little splinter of wood or similar, for example, a broken match stick.
However, the issue is you cannot have any reliable means of *controlling* the aperture of a "G"-lens when it is combined with the K-1. That is, unless the K-1 has a "G"-type CPU in it. The normal K-1 is on the narrow side for that, though. So the next step up the ladder will be the PK-11A. Still no means of controlling the aperture though, unless the ring gets a CPU of its own.