[woodcote]

I think that route is the easiest.

Is the Rally Chrono a two-pin controller socket or three? The two-pin is easy and it doesn't really matter with a resistor controller if you get the wires round the wrong way (trigger & full power). If it's three-pin, make sure you take a picture of the disassembled controllers (donor and recipient) before removing the wires - then you know which to swap. That'll give you a brake circuit, which was only added to the later SCX powerbases.

Good luck