Hi Joe. Yes, if you want your switch to look correct for 70, you'll need to drill out the rivets on your new switch and put a correct 70 black flasher button in it. OR spend high dollar hunting for a correct 70 switch.
If you're not concerned about correctness on this specific part, you could swap on a 71-74 steering column housing to match your switch, OR do some grinding on the new switch to make it fit your 70 column.
