Camaro 69, so removing that 1/2"spacer will raise the back 1/2" correct?
then I could discard the spacer and buy a block the same size and put it under the leaf to utilize the pin. Unless the spacer has a pin then I would just use that.

If I want to go higher than the spacer thickness then I would need to add a leaf I take it.

 

Right, removing the upper spacers and spacing below instead will drop the rearend lower onto the leaf springs, giving more fender clearance by the thickness of that spacer. Essentially "raising" the rear of the car.
The mono leafs have locating pins on the bottom, not the top. So unless a hole/pinned spacer (as I showed) was used, you're not going to be able to recycle the spacers you have.