Its possible that the pulley on the power steering pump is bad. the belt is suppose to run on the sides of the V, not at the bottom of the groove. If the belt has been run loose for some time, the sides of the pulley wear and the belt no longer grabs on the sides. This lets the belt bottom on the pulley and only drives off the very bottom of the belt, and it will slip until everything warms up. Eventually, the belt will slip all the time. If the belt is very low in the pulley, the pulley needs to be changed.

The air injection ports on the 360 heads are under the exhaust ports in the heads. If the manifolds are not removed, the ports in the heads will remain covered by the manifolds. If you cover the large holes where the emission tubes connect to the manifold, you will not have an exhaust leak, as long as the manifold to head is still sealed, and the manifold is not cracked. If you pull the manifolds off, the ports in the heads, under the exhaust ports needs to be plugged. Those holes are 1/4" in diameter, and run up into the exhaust port in the head, about 1/2" inside the manifold surface. Gene