I wouldn't exactly go asking for trade cause Erin allows it.. May get someone in trouble I would ask for Erin specifically...
I dont think Steve Griffiths will do a custom manifold, afaik he is only into services & tune ups? Not sure, talk to Central Coast Turbo Charging, cannot recommend them enough, very very nice people there. I dont think he will build you custom manifolds, but he will definently point you in the right direction. They mainly do Diesel Turbos now.
I would also try Pro Built in Tuggerah/Wyong. I believe they do custom jobs.