Instead of rebuilding one, I would just get another one. I even have one as a backup.
You can send it to Nick at TPC. U know I beat the piss out my tpc20. The thing is...any turbo can break, at any time. There is no single indestructible one. Except maybe an is12
Once you start playing with power and introducing new things to the car its a risk. Sometimes the stock units fail on people in normal situations who don't even know this forum exists!
So take your 20 and get all the support work done to support twhat you want. Eventually you will change the turbo to something at the end of the day. The quest for more power never goes away, it just gets slowed down lol. If it dies then you can just take it out and send it to someone for a hybrid or do something else.
You can make wicked fun power out of a is20. Its underrated imo. I'll take its function over the is38 all day. Especially on track.