[mr48chev]

First and most most important, they should show you current examples of work that they just did on sheet metal items including large body panels.

A buddy took a pretty nice but rusty Model A body down to the semi truck trailer shop that guys in the area had been having their frames sandblasted at and the dude who blasted it pretty well destroyed the body in the process of blasting it because he had no clue how to do sheet metal. He normally blasted 40 ft long trailer frames. The panels were warped to the point that they were beyond repair.

The powder coating shop that does most of the sheet metal including a steady flow of car bodies on rotisseries for shops in the area did have one very experienced guy that did all the large sheet metal pieces. The manager showed me several pieces that had been done that day or very recently and they all looked great.

Soda blasting usually only takes paint off and a very skilled operator can actually remove one layer of paint at a time if they want to. It doesn't do well on rust though.

Some guys like walnut shells as they say they don't create the heat that sand does.

Still sand with a skilled operator will get the paint and rust.

I agree, strip the parts down to the bare naked and clean any dirt and grease off before you take them in.