Not trying to be funny here. The easiest is to sell it and buy it again
I don't have the SD60. I have a bunch of other MTH engines that I did modify to fixed pilots. I did a lot of them differently as parts were available or not.
The easiest fast, and dirty method is just to turn the floating pilot upside down on the correct thickness piece of plastic and trace it out. You cut it out slightly larger and file and sand it to mate.
Some of the stock pilots need drilling to accept the KD mounting screws. The stock pilots require some innovative moves to mount them. On older models I have cut and mounted the frame with the pilot. Some newest models, have body mounts to accept stock fixed pilots. They aren't setup for modified floating pilots. So you still have to be creative.
