Revhard manifolds are actually prone to cracking just as they come from the manufacturer. It should be easily cured by cutting the flange so that each port has it's own flange, and drilling out the holes for the studs to the head to compensate for heat expansion.
Here is also another manifold you can get, but he requests 10 orders before he makes them. Very good quality from what I can tell. It is a direct replacement for the revhard, with much more detail to craftsmanship.
http://www.executivecleancar.com/KAM...fo_and_pix.htm