I have encountered this item of work to be paid by the ton as a composite mixture, which of course will be calculated based on the mix design of: aggregate, emulsion (residual asphalt), cement, water, and field control additive.
Secure a mix design used in your area.
The rate at which it is placed (locally) is LBS/SY.
1/4" to 3/8" is normal depending on the need and rdwy.