Changing the fuel flow screw will also change the timing. Turn it down 1 flat or so (1/6 turn) then set the timing with a proper timing meter.
There is 0 difference between 6.9 & 7.3 injectors in reality. There are different codes, but the differences are very slight (so I've been told) and any of them will work. You'll get no befit chaging injectors, except that which you'd get from new injectors anyway.
IMHO, turning the fuel up on these without a turbo or so way of increasing the air flow is a waste, since you're just wasting fuel, and have a very real chance of blowing the motor up. These NA motor run high EGT's anyway, and more fuel just makes it worse, and if everything is in good shape, the stock setup will give you enough fuel you can burn. More fuel just goes into smoke and raises the EGT's.
Now, you would get extra power from advanced timing, and IMHO, this is the only reason turning up the fuel feel like more power. (that, and you make more smoke so everyone thinks you look cool.
) But, increasing the timing in not good for the motor either. Turn the fuel back down, get the timing set right, then try again.