If your goal is 300 hp, 19# injectors won't cut it and without a target specific cam you won't reach 300 hp with 6-8 psi of boost, if you want to call it good for 200-225 with what you have mentioned with #24 injectors and stay below 5k, you can probably continue, after that everything gets expensive, plus I haven't heard about a rotating assembly balance, I may have missed it, but its the first thing I have done on a performance oriented six.