I replaced all the studs on my WD 45 with hard bolts of the proper length, with a hard washer under each bolt head.
I use Black Gasket-Maker on the threads.
As for the gaskets, I rub Hi-temp Silicone into the asbestos, stick the gaskets into the metal cups and stick them onto the manifold runners.
Makes an easier way to install them and I think the gaskets last longer this way.
You don't want to make the mounting bolts overly tight on the ends, the manifold needs to be able to slip as the manifold expands and contracts. Graphite might be good on the side next to the Head..