WANTED - Exhaust Austin Allegro Mark 3 !

WANTED - Exhaust for Austin Allegro Mark 3, 1275cc saloon Either mild steel or stainless steel. I already have the two branch manifold which extends from engine to bottom of front bulkhead at drivers feet but need remainder of exhaust system which extends to the rear of the car. Anything possibly considered e.g. system to suit alternative models such as 1500cc or 1750cc models