This ^
I've done a LOT of P/Js, and while the initial outlay seems high, the path of least resistance is ALWAYS to not modify either the body or the pickguard, but the circuit only. I get my PJ circuits from John @KiOgon on BC, you'll struggle to get anything like as good quality for the price anywhere else. Don't make the other error of leaving 1xT 1xV with a selector switch, it really limits the options on a P/J
IMPORTANT: measure the width and depth of the cavity into which the two stacked pots and make sure to let John know so that he in turn can build you a circuit that will definitely fit. Some photos probably make this process even more reliable.