I have a 318 with the silver cast manifold and thermostate housing. I want to know how to spruce this engine up. Can I paint it with something like por15 or use an exhaust manifold paint. thanks Jim

if your going to paint the exhaust manifold you need to make sure you use a high temp paint. They sell special paint just for that but even it will peel/wear off in time.
If painting other things on the engine just use engine paint from your local auto parts store. If you want an aluminum look try using a cast iron color. I use it and it generally looks more like aluminum than aluminum color paints because their to shinny.