Review
I just re-read this thread from the top, and want to comment on a few things.
The 12v engine can make considerably more power with the same injectors just by adjusting the pump or changing the fuel plate profile or location. So the version of the Cummins engine in the Ford application may not actually have bigger injectors, but may just have a different fuel plate profile to get the higher HP. I really don't know about this version of the engine. Maybe somone with some Ford experience can help you out with this.
Most 12v guys go with the marine engine injectors, they provide a significant HP increase along with plenty of smoke [if you want smoke]
Resetting the timing is a precision job, the width of a pencil mark on the crank dampener is half a degree of pump timing. Determining top-dead-center can be messed up easily and result in having everything messed up. I'd suggest finding someone in your area with the correct guages and experience and getting it set to about 16 degrees +/- . 5 . A correct set of timing tools costs about $250-300 so if you find someone to set your timing for $150 or so they are paying for their tools and charging for their time. And it only needs to be done once.
You have not mentioned the KDP, and your posts don't have a signature yet, have you taken the front cover off and either tabbed or peened the Killer Dowel Pin yet?? This is an engine killer item. If not put this job at the top of your list of things to do.
The best bang for your buck on a 12v engine is a set of 3k governor springs, and a fuel plate. These two items with timing set at 16* really wake up the 12v engine and put a grin on the driver for many months. And the cost is minimal.
To fill in your signature, go to the 'discussion forums' tab above, click, select 'user control panel' , click and select 'edit user profile' and fill in your truck information, year, etc. This will help us help you. If you fill in your location in NC, you might find someone nearby with tools and experience that can help you with your truck, or recommend someone, or an event nearby.
Hope all this helps, Good luck, Greg L