there is a guy in hotrodders.com called ka67 that did a TT-BBC setup in a chevelle... Homemade headers too...
is it to fit a bu??
if it were me, id do a log style header like schwartx racing uses on his LS7 engines.. fabricated from 2 mild steel bends in each end and two T's in the middle welded onto a flange, with the turbo flange pointing up, and wastegates down at the rear of the engine.. ... they never crack, are easy to make and support 1100 Hp in his ultima... (i bet he will even make up a set for you if you are mechanically challenged and the supply measurements)