If you are going to go bigger on the injectors, I'd recommend something that will also support a larger turbo -- I'd say 750 at least. If you go, say 20g or more in the future 750 may even fall a bit short. No point in replacing injectors twice, IMO.
But I also think you don't need bigger injectors for what you are planning to do.
(Speaking from experience. My hta68 was starting to max out my 725's -- now running 1000's.)