I have an old (not that old really - early 1980's) Raleigh Sensor. The frame is made of Hi-Ten steel. The problem is that I'm used to modern brakes now, so found the single pivot Weinmann Alesa brakes not quite up to scratch. So, armed with a power tool, some HSS drill bits and a set of Tektro dual pivots, I set to work.
Starting point
N.B. You only need to drill out the rear side of the crown. The front stays the same size.
After a 7mm drill bit
After an 8mm drill bit
Dual pivot lovelyness
I wouldn't recommend this procedure on anything other than a steel bike.