Curious what you experienced guys do. I have some older but good buckets with 3" pins, but coupler will be 80mm. 3" is like 76mm. Should I waste the effort to bore the bucket for bigger pins or put sleeves on? I highly doubt we would run those buckets much. One is a slimmer trench bucket so way less dig force anyway.
As long as the coupler is a multi-grabber, you will be just fine. They hold pressure on the pins. You may also be fine if it's a dimension specific coupler, won't know until you try it.