set the 'new' blade "in place" slowly drill from BOTH sides, a little at a time, so the holes "line up" (meet in the middle) most folks tend to drill off to the side if going in from ONLY one side, nature of a drill bit that small in diameter......it'll 'walk"..................or use the proper sized drill bit, mark the sight blade, again, from BOTH sides and drill it ( the blade ONLY) in a drill press....couple of options there....if I recall those Speed Sixes, and Service Sixes do NOT have a very tall sight anyway??? no reason for any company to be making/marketing, stuff , for an "obsolete" item............................I'd bet , the gun would end up shooting low then......most we've come across that had 'redone' front blades' do.....
Paint the back of the front blade with DayGlo orange or such if you have trouble "seeing" it...... :wink: