I don't have any higher levels for boosting right now, but have found a couple threads with some info you might find useful if you haven't seem them already.

https://www.dual-boxing.com/threads/56328-Good-way-of-using-60s-to-boost-you


https://www.dual-boxing.com/threads/56345-Best-(and-safe-non-bannable)-way-to-boost-two-mages-using-three-60-mages