The basic valley pan gasket is stamped steel. No matter the brand. Will need to be specific to the 413/426Wedge/440 (raised block) or the 361/383/400 (low block).
On the 440 6bbl motors, which used an aluminum intake manifold, FelPro has a set of additional paper gaskets to go with the steel gasket. The paper goes between the steel gasket and the aluminum intake, to prevent wear between the aluminum and steel, during the hot/cold engine temp cycles. They can also be used on the cast iron intakes, too, if desired.
For an extra bit of sealing, you might get some black high-heat silicone sealer and put it into the recesses/beading of the steel gasket. Smooth it out with a gasket scraper. Let cure over night, at least. When you put the intake valley pan gasket on, then torque the manifold down, that bit of silicone will press against the cyl head, when the intake manifold is torqued down, for a better seal. Not necessary, but can be done anyway.
If the insulator "bag" is still useable, you might install it back under the center of the intake manifold from where it originally came from.
DO torque the intake manifold bolts in sequence, in "steps" of torque. Start with snug, then progress from there in two different torque levels until the stated torque value is reached. After a few hot/cold cycles, re-check for good measure.
Enjoy!
CBODY67
