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