Control box, ? changing from RB 310 to RB 340 plus wiring when changing to negative earth

Hello guys, as part of my Mk 2’s restoration (1964 3.4) I am changing to negative earth.
I have checked the archives which I found useful but there was no mention off the control box.
Question is can I retain the preferred alloy RB 310 unit and does any wires need changing.
Please advise. TIA.