Here's a little follow-up. I tried Calyx Manifold Dressing (type that in Google, you'll find it) about a year ago now and it is great stuff. Gives the cast look you want, stays soft, won't burn off or crack, and real easy to redo a few spots if you need to. Great stuff.
I've driven about 1000 miles with it on. Only problem is when wash truck and water gets on (drips thru hood hinge), and let set a few days after, some little rust spots form. Probably because I didn't rub in the Calyx real good at first. But only takes about 10 minutes to make look like new again, right there on the engine, not unbolt the manifold. I've just learned to start up engine after wash, so manifold dries off quickly. Looks like new a year later.
