I don't know if they will fit as is. It seems to be the billet manifolds were all made to fit the Bonnie's. I am using stock manifolds with the rubbers flipped over.
If you want to take a close up picture of what you have now that would help. The other thing would be if the angle has to change, your billet manifolds could be machined to suit. I could probably find some milling machine time.

05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter