I need the kit part numbers going from LP to natural gas for the orifices on a P2B918DEM3BB GE Range
There is not a kit for going from LP to Natural. You will need to replace each orifice or orifice holder. The part number required are for the Left rear WB28K10022 orifice only, Right front WB28K10030 orifice only, Right rear WB28K10390 orifice holder with orifice, Left front WB28K10388 orifice holder with orifice, and the center burner WB28K10300 orifice holder with orifice. The regulator would just require flipping the cap to natural.
I need a kit part number for LP conversion for the top burners, broiler, and oven orifices
The lp orifices for your unit are WB28K10032 for the front burners, WB28K10031 for the right rear burner, and WB28K10215 for the Left rear. The oven orifices would be adjustable in which you would tighten down the orifices and opening the shutters. The regulator would need to flipped from Nat to LP.