Some purists are probably going to have a teary at me about this, but you could use any bolt, like you said as long as it is the same.
there should be a big o-ring in the centre whihch should be replaced.
And when you tighten them you should do it in a star pattern so to speak, there prob would be a specific torque setting as well, you can figure that out from the mating material, bolt type size thread pitch etc...