I've personally have not seen an OEI CRZ above FL240 on the NG or CL, maybe FL245 when empty on the NG.
So initially, you would drift to <FL240.
The statement regarding the over boost is talking about what thrust protection is available when the EEC is in the hard mode or alternate. To protect Boeing, they include the statement about when to over boost the engines. It has nothing to do with Engine failures.