Where to start???

I'd get the body on the go first but there is nothing wrong with working on the engine if that is what you are more interested in doing right now. Obviously some work just doesn't make sense to do right now. Some suggest just picking one thing and working on that rather than trying to have everything on the go (unless you are sending it out). Personally I like to have a few different jobs going at the same time in case I get stuck on one waiting for parts or just plain tired of it. Its nice to plan future jobs out and make sure you have the right parts and know how before you get to it too.