I wouldn't hesitate to add my voice to the idea of renting a blaster or buying some sort of hobby-grade blaster and doing it yourself IF YOU'RE BLASTING THE FRAME! Otherwise you can very easily destroy your vintage tin. I've read so many stories of so-called "professional" blasters burning through on pieces, dimpling parts, and stretching panels until they are beyond repair.
Take care with your project.
~rocker~
