I am putting complete running gear out of a 90 vette into my 68 Firebird, problem is I do not want headers, and drivers side vette manifold hits gearbox, does anyone know if standard rams horn manifolds will fit? I know its a l98 engine which is all the same design but the vette manifolds are high performance and its aluminum heads so any advice would be more than appreciated!!

original Camaro manifolds will fit, the Ram's horns won't.
If you don't mind spending some $$$, check out Sanderson.