I would avoid blasting the sheet metal if possible. Especially if the paint build up on the outside is minimal. A good body shop can quickly take off the paint with a D/A.

My A12 was only blasted in the floor pans, jambs, engine compartment. I was wanting to soda blast my whole car, but after much discussion, cost, and available expertise, I chose to just the harder areas.

If you do want to blast the outside, I think Soda or Plastic is the best way due to heat build up.