Newbie here, living in the center of the desert. I'm prepping the head exhaust-port surfaces [ is that what you call them? ] for the install of an exhaust manifold (don't have it yet). Using 80-grit sandpaper: is 80 grit OK; good or bad? Would have to order a finer grade by mail. I might be able to borrow a Dremel tool. (There are no professional mechanics or machine shops within 60 miles, and only one little store with little to choose from.) Have a Fel-Pro exhaust manifold gasket: better or worse if I use a "sealant," RV-something or other? [ 1990 Ram 50, 2.4L w/ fuel injection and SOHC ] Thanks to any respondents!