I have done both my 59 truck and my 47 cj2a with a big grinder and a knotted cable wire brush. In fact - it took like 3-4 brushes for each of them. I preferred it because I didn't want to have the media coming out all over the place. Using small cup brushes you can get in the nooks and crannies.
I then sprayed it with metal-prep (just posphoric acid) and then put zero rust on the truck and chassiskote on the heep. Both are lasting good. I'd give the edge to chassiskote as its harder.
However, having it done is a lot easier. And for $100, that was less than the grinder, wheels, and time spent.