The first place I thought I’d start with the Avionics kit is the very last chapter, 58. This chapter is how to retrofit the autopilot control knobs into the center panel. (Note: the autopilot is typically controlled with soft knobs on the primary display, and this is an optional kit that provides dedicated hard knobs on the panel.)
The majority of the instructions are to help with the retrofit process, but I haven’t gotten anywhere near that stage so this is actually much easier. The picture below shows holes drilled and lines scribed & taped prior to cutting out the panel for the two modules. The yellow tape is going to be the edge of the cuts. The blue tape is “don’t cut here!” since the yellow tape is wider than the slot that will be left between the two cutouts.
Center Panel prior to cut outs.