Hello and welcome.
Issues with putting that sort of front end on a K:
The GSXR has much less fork offset than a K (which itself has quite a lot) This is the amount by which the fork legs are set forward of the steering axis, as you look at the top of the yoke. If you compare the two sets of yokes (have a look at pics of both sets of yokes on oohbay for example) you can see that the GSXR yokes are much flatter.
This isn't a massive problem as regards the steering geometry: the GSXR yokes will give more trail when installed, which will make the bike more stable (not that it needs it) Of course, more trail also means that you will have shortened the K's wheelbase, which is no bad thing at all.
The real practical issue with this sort of conversion is that, by moving the fork legs backwards with respect to the steering head, they will be much closer to the petrol tank and this can have a big restriction on steering lock.
This is compounded by the actual diameter of those big old USD fork legs - they are much thicker than the K's 42mm or so, and this will make them collide with the tank much earlier as you steer onto full lock.
There is currently a bike for sale on oohbay; a very expensive 'pro-built' item with these sort of USD/short offset forks. In one of the pics you can see just how little steering lock it seems to have.
FWIW I have done a similar conversion myself, and I ended up cutting the tank mounting brackets off the frame and moving it rearwards by 14mm. Steering lock is still limited, but the bike is useable. I do wonder if that's the case for many of these specials that you see?
Try it and see, is my advice. This is just a heads up.
Edit: looking for a few explanatory pics. Here's a USD-forked special, but note how the builders have used a custom set of yokes that seem to keep the K's original large fork offset - this bike will go round corners!
The builders are called Dixer parts, and I hope they appreciate why I have posted this picture, and don't get too concerned about copyright.