FYI, here's what Dynamat recommended when I inquired about which products to use. And SuperD, those scissors at Harbor Freight worked perfectly!
"We recommend two products for the engine cover:
Xtreme and Hoodliner.
First, install the Xtreme. This product will damp any vibrations/resonations in steel, fiberglass, or wood panels to reduce structure borne noise.
Over the Xtreme, install our Hoodliner. Hoodliner is the 3/4 inch thick, peel and stick material you mentioned. Hoodliner used with the Xtreme will do a good job to reduce engine noise and heat."