I would paint the engine compartment all the way back to where the floor meets the firewall where the bell housing hump meets the floor trans hump (it gets the front of the torsion bar cross member pretty good too) and the side and bottom of all the frame rails. The factory shot at about a 45 degree angle from the bottom side to get under the frame rails and so they could get the bottom of the rockers with a good coat. It got the side and bottom of all the frame rails as well even though it may be a light coat on the bottom (the sides usually are pretty well painted). My painter painted the inside of the wheelhouses and the frame rails on my car before he did the outside of the car. There is some overspray on the underneath of the floor as a result.