Holy smokes, you obliterated that clutch basket!!
When it fails like that, I understand you can replace the basket, rebuild the clutch, etc. But I would assume you are still going to have to split the cases (at a minimum) to collect all the broken metal bits and wash out all the fragments?
What is the minimum that must be done?
When a basket explodes like that you definitely want a full teardown to wash out all metal fragments and that's what I did. If just one or 2 fingers broke and they stayed in big pieces and you found 'em all, you might get away with a good flush.
Mine was very ground up so I experimented a bit. I drained the oil, filled it a few times with kerosene and shook it around and drained it to see how effective it would be. Then I tore it down and split the cases. Most of the metal did wash out but there was a lot clogging the oil pickup screen and there was chunks of metal stuck to the magnet inside the flywheel and between gear teeth, forced in as the gears meshed. Basically if you suspect small pieces of metal are floating around you need to tear down completely.
Another thing I thought of is the kickstart mechanism. I broke the little arm that holds the spring in place and it jammed in the clutch basket gear. It's super hard so it didn't get chewed up and I just replaced it and changed the oil.
My point is that it could be something simple and there's nothing worse than finding that out just after you split the cases.
A full teardown is not bad if you have a bit of mechanical experience and take your time. There's lots of pieces but the manual is pretty good. I used the teardown as an excuse to pop in a set of hotcams and a 430 kit.