Can't speak about Ford in particular, but I can tell you two things you'll
want to look into.  A radiator with more capacity for the engine, or perhaps
an add on oil cooler. And second, an good transmission fluid cooler in front
of the radiator down stream from the original cooler.

Whether you go with a 7.3 or a 6.0, the very first consideration is the size
and the weight of either.... these are much heavier and larger than gasoline
engines. While they run quite cool when lightly loaded... they generate
monster heat when worked - both for the cooling system and in the region of
the turbocharger (over 1000 degrees F, at times).

Stir in the electronics nightmare..... for the 7.3 there will be the IDM as
well as the PCM..... related wiring. The 6.0 has a PCM to worry about (both
the FICM and the GPCM are engine mounted) as well as it's own wiring
requirements.... Both will need an extra battery, a frame mounted fuel pump
(the 7.3 will need a tank with a DTRM in it..... all this is in the HFCM for
the 6.0).

I would be awful tempted to forget the swap route and buy what I needed....

If you decide to forge ahead...... the 4R100 that you will need for the 7.3
*may* have a mechanical diode rather than a sprague one way clutch... If so,
this should be changed out while you have the trans on the bench....

HTH.