I've never had to attempt to get one one these locks out but I'm sure there must be someone on the site who has !. Were it me I think I'd remove the forks and drop the bottom yoke out as there's every probability that drillings would end up there. Having given it some thought I'd 'go in' with a 7mm drill in at a low angle and rising up when an entry has been achieved in an effort to centralize the hole that you are trying to make in the lock barrel. After measuring my lock I reckon it shouldn't be necessary to drill in further than 25mm because by then you will have just passed the steel pin that's holding it in, hopefully dislodging it. Using a stiff piece of wire (push bike spokes, tough as Hell, cheap, no tool box should be without a few) bend a 90 degree hook on the end, insert it and see if it registers in the mechanism to try and extract it or if the steering stem is out, tap it right through using a suitably sized drift. Can't think of any other way of doing it..........best of luck.
