I've heard some rec Simple Green?

Simple green will work, I prefer citrus degreaser. Home Depot sells both, the citrus degreaser is under the "Zepp" brand name. I think it is around $3-4 in a trigger bottle. Make sure the engine isn't too hot, or it will evaporate to quickly.

Mark

Once you get the grease off, the only place you'll find rust is on the block. But if it has been coated with gunk, it should have protected it from rust, and it should in theory be good. A good coating of Rustoleum, will brighten it up. I used to use it on the inside of blocks for oil runoff. But using synthetics, and hotter temps now, I don't anymore.

Mark

A mild solution of phosphoric acid will take off rust. You can find it in a concentrate at a auto paint supply houses. One brand I used was R-M metal conditioner MC801. Since it is generally used for body panels, I'm not sure how it would act on hoses/gaskets and such. Make sure you dilute it WELL, and RINSE thoroughly! Wear protective gear, it is acid!

Mark