b motor into a body

The only stock exhaust manifolds that fit that I’m aware of are the stock 383 manifolds. Others will not clear the steering column and interfere with power steering pump 383 manifolds are pricey, expect to pay $1200 to $2000 for a pair. And headers that fit are not common. Ones that do are fender well headers and if you cut holes in the fender aprons which you need to do to install them, you are weakening the unibody of the front end. Fender aprons are structural.