i think you will find that drill will only run at about 70mph?
depends how much calibration needed but you could get through a few drills?
possible solution is buy second hand speedo slightly over what your correct mileage is, buy a third speedo and run that until the bike has reached the total miles on the replacement speedo
i.e damaged speedo (a) says 5k
replacement speedo (b) says 6k
use a third speedo(c) for a 1k unitil A=B then sell on speedo C
speedo (c) could be in kilos and convert them, kilo speedos are very cheap, coz no one really wants them