The phrase "of a scale" is correct and usable in written English.
It can be used to indicate something is being measured on a specific scale, such as "the temperature of a scale from 1 to 10".
"On that kind of a scale, we're still really untested".
Leadership in children's services faces new and complex challenges of a scale not seen before.
The private persons interviewed during the course of this investigation represent extreme ends of a scale.
This facility is of a scale beyond the wildest dreams of many of our international competitors.
It was the kind of a scale that tells your fortune as well as your weight.
I don't have a tax cut of a scale you're talking about".
I don't have a tax cut of a scale that you're talking about.
His crimes were of a scale that only a person of means could have pulled off.
"The decisions they make are of a scale many times what the consumer does".
"These are cuts of a scale which we have never seen before".
The Docklands Light Railway still has the feel of a scale model.
