I avoided actual manifold bolts and got 12.8 grade hardened bolts of the same length with a washer. Did that on my '02, lasted 7 years, took them out to remove the manifold before scrapping it, none broke or stripped.
The bolts you want... need to be 5 MM L-o-n-g-e-r if using the Dorman Exhaust Manifold. These Alternative After-market Fasteners are of Grade "8" (10.9 Hardness) Strength and are M8 X 1.25 X 35MM in Dimensions, Here are some images of them and they can be sourced by the data on the Box End-Bolt Exemplar Image.
Please Note that the underside of the Bolt Head Flanges are WIDER and thus they will spread out the contact load against the MLS gasket much better. The Upper Bolt Shanks are also UNTHREADED, making them Stronger and More resistant to Flexing, Rusting and Snapping Off due to excessive exposure to Stress, Water Exposure and Temperature Changes vs. the Shorter, Stock, Fully Threaded flavors: