bear in mind folks, creativity went out the window many moons ago at out airlines, due to insurance liabilities, etc...unless a specific procedure is outlined in a FCOM, or some other approved company publication, a power back, while physically possible, would be foolhardy at best...727's DC-9's etc did it regularly in the USA anyway, it was discouraged in the 757/767 FCOMs due to FOD ingestion possibilities.. (although apparently some operators did)...