There is stuff called POR15 for your frame, or rust mort. There are other frame paints that will go on like glass, if you have a frame there all cleaned up I'd look into one of the higher end products. Search the web for prices. I have used POR15 and wasn't all that impressed with it, but I wasn't really working with a lot of rust. As far as painting enines goes...I have painted many engines and found that the key is to have the block and heads absolutely clean and dry. If at all possible paint it in the sun too. USE PRIMER if you do, the paint will stay on the engine. When I haven't used primer the paint came off in spots. As far as paints go, I think those high temp paints are a waste of $ and never look as good. I usually buy a qt of rustoleum in the color of choice and thin it so I can spray it with my paint gun. I always end up with the nicest looking engines.
~Captain's Log~