I just did a rebuild on a 7.3 engine. The engine had many miles on it to say the least with lots of blow by. It need a complete re-build.
I used Mahle pistons in the re-build. Mahle makes a great piston for the Powerstrokes. The Sealed Power rings came with the pistons also. Sealed power pin bushings were used for the engine. Melling oil pump. You have to have good oil pressure in the Powerstrokes so I would use a Melling pump in any type of re-build. Clevite/Durabond bearings for the cam, main and rod journals. I try to buy American parts when I can even if it costs more.
My 7.3 had many many miles on it. Once the machine shop disassembled the engine for the machine work, they measured the crank and informed me it didn't need to be turned. I went over and measured the crank myself and was impressed that the crank didn't need to be cut at all. The timing gears and the roller cam don't ever wear out it looks like, if regular maintenance was preformed on the engine. The connecting rods were perfectly round also with no re-sizing work needed on them. New Ford head bolts are in order or some head studs, old bolts are sent to the recycle bin. New lifters were installed too. Too many miles on the lifters to trust them in a rebuilt engine. I believe the lifters were Engine Pro guys.
New valves and valve springs went into the re-built heads. The valves were worn out and cupped very bad to where reworking them was impossible. The valves I used were S/S valves and springs. Made in Brazil and quality pieces. In fact a lot of International engines are built in Brazil for American Ford trucks such as the 7.3 were. New valve seals come in the gasket kit and the old retainers, keepers, rocker arms and push rods were used in the project. Inspect all of the old pieces that you are going back in the engine for damage or wear. If any get rid of them and get new pieces. Just like a chain a engine is only as strong as it's weakest link.
The gasket set was a EPWI guy. It is the parent company to Fel-pro I believe and markets gaskets sets to machine shops mostly under this brand name. Mine was a stock re-build with new Alient injectors installed also. This should be a good starting point for parts needed for a stock rebuild.
I would also add new injector wiring harness for each side to be installed when the engine is out and easy to get to. The F-250 will be used for towing purposes mostly. My engine builders here in Houston does great work. Very dillegent in their work which you do pay for. Get a good machine shop that will do the job correctly is at the top of the list when rebuilding your engine.