I have 41T. From what I have heard, that is a magic number for reduced vibes and increased speed. The 36T is great for small hills and for the flat lander that want really high speeds. The 41T is almost as fast and still climbs great. The 41T is not expensive at all. Enjoy the ride...
I ran the 38 tooth Bikeberry cog today. I had to mill out the center hole to fit on my hub like the original (they were close, but not the same size).
Drilling the holes was a pain. I suggest marking them all with a magic fine point marker, and drilling pilot holes on 7 (2 will overlap the original 5 bolt circle). I used a Vise Grip to hold them for marking. I used a Rat Tail file to elongate the overlapping holes. I used small flat washers on the screws, under the screw heads, to compensate for the oversized/odd holes, and the others to match.
Well, I got it done, and it works well. The 48cc (well broken in) tows along about 3-4 mph faster and takes off just about like it did before. I topped out at 33mph on flat ground, wide open, after moving the C clip one notch richer.
I don't think the 48cc can work with the 36 tooth or 32 tooth, unless you have some power add-ons like a performance pipe and engine mods.
If you can, go with the pre-drilled flat sprockets on the vendor websites like Dax etc It would be way easier, and you can flip the sprocket when it starts wearing, for more life.