Magnum head and exh manifold ID

Keeping it simple is using the 360 engine I have IN the car, and swapping a set of 360 mag heads I got free, will have to aquire an intake but cost wise the cost of an intake and some gaskets to get a boost of compression and newer port and head design to make more power, sounds a hell of alot cheaper than trying to track down a running and built 360 magnum and then trying to get it in to the car.