hi mate check out sitech racing ,his web sites helpful and his done zvh and st170 head mated to rs focus bottom end http://sitechracing.co.uk/products-ford.asp also check out stu collins 1.6 rs turbo https://passionford.com/forum/restor...73-122mph.html . only other thing to sugest is using r5 gt turbo carb or 2 mated to cvh there is a few fiesta done like this could be a cheap starting point . ive had 11 renault 5 gt turbos there great