My preferred method is chemical stripper followed by sandblasting. Cover the painted surfaces. Use the thick solvent based "aircraft" stripper found at some of the big box stores. Its good stuff! A gallon should do the engine compartment. Paint it on a small area with a cheap paint brush. Let it sit for a half hour or so, then scrape the surface with a razor blade scraper, changing the blade as needed. Wire bristle "tooth brushes" also work well. I use a large shallow cardboard box and allow the scrapings to fall into the box to minimize cleanup. Plastic sheets on the ground will also work.

I then sandblast the areas that are rusty or still show paint. I use a cheap suction feed unit. My air compressor isn't all that big. Blasting it all would take too much time and leave me with a beach afterward. The majority of the surface comes clean with the stripper, the blaster cleans up the other areas.

Prime with what you like afterward.

Making a mess is part of the fun. A little planing upfront will minimize the cleanup. Best of all its super low buck but you will have some time invested.