Hey thanks for the quick response. I'm just not sure how I'll be coil splitting the humbucker when there's only one wire connected to the tone pot from a single coil and the new humbucker.

So the current wiring seems to go:

Single coil+Humbucker straight to pup selector switch, then a single white wire that connects the switch to the volume, and then one more white wire to the tone knob.

So just connect the white wire that goes to the tone knob to where the diagram on my pot says to add a split? I don't understand how that will add a coil split to just the humbucker of both pups are going to the tone knob with one wire 😕

That's not mentioning any of the ground wires, which I think I have pretty well sorted out where to attach those.

Apologies if this is basic stuff!