Thought you might be interested in how I removed stuck valve guides on the 8N. If the guide is stuck, you can't push it down, and If you can't push the guide down, you can't get the clip out, and if you can't get the clip out you can't drive the guide up and out. I tried all sorts of bars and screwdrivers on the top of the guide through the inlet and exhaust ports but no movement.

The inlets are easy. Put on the spring compressor with the valve in the head and drop out the collets. Then the valve can be pulled out. Then using the compressor, wiggle the collet cap and spring out over the guide. Then the guide can be drive up or down - down is easier.

The exhaust with the rotator is a different beast. With the valve in the head, when the spring is compressed, the collet cap comes into contact with the guide before the collets are released. In my attempt to drive the guide down, I snapped the end off the guide off - it is cast iron so broke easily. This gave me a new opportunity. I carefully drilled into the broken off part of the guide with a 3/32 drill in three places around the flange on the end of the guide and by drilling between the spring coils. This size of drill missed the coils of the spring. Then with a sharp small chisel, I beat across each of the holes, breaking the broken part of the guide into three pieces. I could then wiggle the broken guide parts through the spring and out.

Now the spring compressor could compress far enough to get the collets out, as the valve guide was much shorter than before. The valve was removed and then the spring wiggled out like the inlets. Then I could drive the guide out from above. Once it started moving, it was easy to remove.

Good luck!