You have another issue you need to consider which will greatly effect which turbo you use and your ultimate power level:
You have a 2003 7.3 L powerstroke which means your engine uses PMR
connecting rods. They will not handle the power like the old forged rods will. They are perfectly fine for their intended stock use but not so much when you want to start added tons of power. Most consider 400 RWHP
the max they can handle. Given that the 38R can easily push enough air and clean up enough fuel to surpass those power numbers I can;t see you needing anything more, that is, unless you do plan pulling your engine to swap out your rods. Go with a bigger turbo and fuel and chances are at some point you will end up dumping your bottom end all over the road. Or you will have to keep it tuned down and thus are wasting money on potential you can not use. We are lucky to some great guys doing tuning now that understand the PMRs
and know how to create tunes that greatly reduce the pressure on these rods and still get good amounts of power at he same time: Matt, Johnathan @ Swamps, Beans, Bill etc....
Given that 238 80s with a 38R with supporting mods can get you to knocking at the door of 500 HP I can not see the value in spending a good sum of extra money going to a Hypermax type kit setup to be able to use the various other turbos out there, again, UNLESS you have plans to eventually pull the engine and swap out he rods. If you plan to do that the engine can be kept tuned down so you don't loose your bottom end until you do the upgrades. Even with the 38R 238 80s you will have to keep it down some as it has the potential to add power beyond what the PMRS
Looking at Turbos of even greater perf is overkill given the PMRs
. The 38R and 238 80s seem to be a proven combo. The 238's can be tuned all the way down to stock and also cranked way up to 500hp levels. They also can be tuned to give better mileage than stock and very smooth idle and great streetabilty for a DD.
I am sure others that have tons more experience than I with real hands on time with the various combos can steer you to the best setup to achieve your goals.