security for 1990 Cooper

[xcentric]

So, have just acquired this, and am thinking o cupping the security. Evidently it once had a Piranha alarm, but that seems not to be present now, except the ultrasonic sensors.

Which aftermarket alarm and immobiliser is worthwhile, or is a disk lock (the circular one) the best bet? Anyone fitted a removable boss and refitted the original Cooper steering wheel, and if so which removable boss fits?

I know I can take out the rotor arm for longer stays in car parks, but that's a pain on a daily basis :-)

all suggestions welcomed.