With the right mold preparation, you can use one set of ejector rods in every machine. One this is done, you can keep the rods in the machine and use the same ejection retract position for all your molds.
Issue: Most of your molds use ejector rods to push the ejection system and you always have to change and adjust ejector rods during each mold change.
Resolution: Spacers should be added to each mold which screw into the ejector plate and are flush with the back of the clamping plate. If ties ejection is used, all the spacers should have the same threading for the knockout rods. Then each machine can have ejector rods machined to be flush with the movable platen when the ejection retract is in the back-most position.
Additional Information: As for the rods and spacers, I recommend they be machined out of Col-Rolled Steel to ensure their strength and endurance.