|I have an IPP Stage III setup in my red track Zed. Spun #5 bearing at the track on my original motor. Sent the block down for IPP rebuild. Tracked it hard for a year after the install.
Spun #5 again at Spokane raceway. Deduced it was an oiling issue with the crank.
Had the engine completely rebuilt locally with a different crank in 2012. No issues since after dozens of track days.
Go IPP if you can deal close with them, for those further afield, I recommend finding a decent local engine builder if you're going for high Hp/ high abuse engines.