Choosing deplacement of the pump is limited to 2 things....how patient you are waiting for things to happen, this sets the minimum...and what is the maximum power you can load the PTO with before bad things start to happen, this sets the maximum.
Is the winch hydraulic ?
The setup of the boom is not critical in speed but if you have a hydraulic winch you want it to move faster then a snail in a stone staircase...