It depends on how much power you want to make. The draw-through is limited to about 10 psi, while the right blow-through setup will go to 50 psi if needed. Of course that's an extreme example, but it could happen. The carb mods aren't extensive: a solid float, drilled power valve and removal of the choke horn is really all that's needed besides a rebuild to make sure the gaskets are in good condition. The draw-through is simpler and easier, though, with no intercooler or blow-off valve to worry about.
EDIT: I'm talking about turbos, not superchargers. The draw-through is much much easier with traditonial superchargers. The Eatons don't have sealed bearings though, and can't be used draw-through unless the bearings are changed.