[TR] soda or bead blast

[Frank Fisher]

working on a friends 49 mayflower.
trying to clean up the undercarriage.
no rot.
little surface rust. original california car.
lots of desert dirt and grime
lots of undercoat.
whats the best way to get back to bare metal? 
or just clean the undercoat to accept another coat where it flakes off?
known locations in southern california that do this work?
other options and opinions welcomed
thanks
Frank