RG58 spec BNCs typically accept up to 5mm outer diameter cable, as that is the OD spec of RG58 co-ax.
Linn's T-Kable has a specified OD of 6mm.
Personally, whether T-Kable can be persuaded to fit, or no, I've always been concerned that a 'fat' pair of tonearm cables aren't necessarily the best thing with springs in compression suspended sub-chassis decks like the LP12; that is, despite what Linn claim re the cable being an integral part of the suspension systems stability/acts as energy sink, etc.
BTW, assuming your Ittok lead is an original, its capacitance is already ideal, if not irrelevant, for your MC cartridge.
P.S. Naim's suggested BNC plug is RS Stock No. 546-4257.