Replacing an over the range microwave with a wall range hood
The measurement that is relevant is the height of the bottom of the hood above the stovetop. This will determine what you would need to do to connect a given hood to your existing ductwork.

As far as the skill level to install a hood in a space occupied by a microwave oven, 25 years ago I did a similar project and I am not a skilled carpenter. I removed the 1970 builder's single unit range with double oven and installed a Vent-A-Hood (basic model) over a basic GE slide in electric range with single oven. I chose to put the bottom of the hood at 29" above the burner surface which I have found is too high for this quality of hood. A height of 24" to 26" would have allowed good visibility of food in deep pots on the back burners, but would improve effectiveness of the hood and would possibly decrease the noise level by getting the bottom of the hood below ear level.

To determine what height works for you (which depends on the height of the people doing the cooking and the depth of the pots) I suggest using a tape measure or a piece of cardboard across the opening to determine that you can see into the deepest pots you will use on the back burners.     


  High-capacity range hoods are typically installed between 24 and 30
  inches above the cooktop, while standard models are installed on
  average between 18 and 24 inches above the surface of the cooktop.
  
  . . . Sometimes contractors prefer to measure the height of
  the range hood they are installing from the floor rather than from the
  surface of the cooktop. When this is the case, the bottom of the range
  hood typically measures 60 inches from the floor.
  https://www.hunker.com/12269148/what-height-to-put-a-range-hood


EDIT

You can arrange for the manufacturer of your kitchen cabinets to provide you with a cabinet which would support the hood and enclose the ductwork and the electrical receptacle for power to the hood. Then you could decide whether you want to try to install it yourself or hire a carpenter to do it yourself. Be aware though that measuring the space for a cabinet unit to fit between two already installed cabinets is tricky.