You don't need to invest in sand blast equipment or pay somebody to sand blast. As said above, degrease and paint strip. Clean up the paint stripper with mineral spirits, and dip in Evapo-Rust for a day or two. Clean up the Evapo-Rust with mineral spirits and apply a phosphoric acid such as Rust-Cure or Ospho. Clean off excess phosphoric acid with mineral spirits again and paint.

I had planned to get a large air compressor and a big sand blast cabinet, but after working with Evapo-Rust, there's no need. Evapo-Rust isn't cheap, but it's a whole lot cheaper than a large compressor and a big sand blast cabinet. You can buy 5 gallons for $80 from northerntool.com with zero freight cost if you pick up at their store. Even 50 gallons at $800 would cost quite a bit less than a big air compressor. And the results are just as good or better.

I did 5 wheels like this. Works out to $16 a wheel just for the Evapo-Rust. And the Evapo-Rust isn't depleted yet.