I've only done a few 617's but I remember heating the new crank sprocket to 250 degrees and dropping it onto the crank snout like you would on a VW or Porsche crank.
The keys are dirt cheap and the crank sprocket isn't bad. I'm all for not wasting money but how often do you pull your crank?
There should be no play on a new one.

BTW, have fun with that rope seal