A ford timing chain either lasts forever or explodes early. Pretty unpredictable. I remove on from a '76 302 with over 100K miles on it that still looked pretty good. Personally, I replace them if I'm in there. Otherwise I don't worry about them. It's not like a timing belt on a rice burner. As for the cam, there are plenty of good choice for your application. They used to be called "RV" cams, designed for low rpm torque. Call the tech line or peruse the catalogs of any of the top companies for good suggestions. But, if it were my car, I wouldn't bother. Upgrading the cam without changing heads/intake seems like a waste of time and money. The right heads and intake on the stock cam will net you 400hp. Even changing the rocker arms won't get you enough to make it worth while unless you've got the right parts to take advantage of it.