It wasn't oiling issues, it was weight. The KL turned out to be heavier than the BP, and the minimum weight in the class is lower for a BP due to lower displacement vs. the KL.
And he was having a hard time making the power he wanted n/a. And if boosting, may as well just go BP for autox use.
He probably did mention oiling issues at some point, though. I remember he was asking around almost a year ago about spinning a KL to 9000rpms, and yes, at that point, oiling issues do pop up.