"perfectly level" is correct and usable in written English.
You could use it to describe an object that is perfectly even and flat. For example, "The desk was perfectly level after I adjusted the legs."
It has to fly perfectly level".
Though the banner seemed perfectly level, they kept finding flaws.
When the tool is perfectly level, or true, the bubble will come to rest between the two lines.
When they returned after a day of sailing, it was high tide, and the gangplank was perfectly level.
But the oceans, even when unjostled by wind and waves, are hardly perfectly level from one place to another.
The i-Glass countertop created by 3Di, a Florida company, may not be perfectly level, but that's the point, said Ken Marsak, the company's owner.
In an otherwise perfectly level-headed summary of the current state of Eminem's career, the Independent's Nick Hasted recently reminisced about the fringe benefits of even the most tangential association with Slim Shady at the height of the Detroit motormouth's early-noughties notoriety.
You have to feel a bit sorry for the American centre-half, who seems to be a perfectly level-headed and pleasant bloke, but also somehow falling over at all times, to the point where you suspect there's an old woman with a grudge and a SportsAccess subscription doing bad things to a little dolly Tim Ream in a trailer park somewhere in rural Nevada.
Managers observe and verify workers' training levels, but they are unable to monitor perfectly the level of effort that workers put into the production process.
It seemed perfectly my level — mellow but challenging".
On one perfectly entertaining level, "The Witch of Edmonton" is like a 17th-century edition of The National Enquirer.
