Kurt made the point earlier but it gets missed often in discussions re: spine and adding weight to each end of a shaft. The spine of the shaft is determined at construction. The dynamic spine is determined by everything else that happens on or to that shaft in making and using it. Front weight, rear weight, draw weight, length the shaft is cut too, cam efficency, etc. all play a part in the dynamic spine of the shaft and how that particular arrow is going to tune given the setup it is being applied too.
While Mr. Price is correct that adding rear weight is going to lower the FOC of the arrow, what wasnt mentioned is the increase in total arrow mass and it's influence on momentum. With that 340 shaft, if it is tuned at this point and you want to increase the point weight by say 25 grains, you may find that you need to increase the rear weight with a lighted nock to keep it tuned. I think you for sure would find that increasing front weight and switching to feathers would destabilize that arrow and reduce accuracy. Maybe not to the point that you couldnt hunt with it but certainly to the point that efficiency and penetration is reduced. Everything is a give an take and the only way to find what works best for you is to test different setups in your rig.