Post 1986 volvo 240's had a factory insulation pad built in and considering the size of the 240 hood vs the toyo hood you should be able to cut it down to fit.

If you look in any auto parts store they have the flat head (quarter coin size) push in plugs (they kind with the fins in teh shaft) that shoudl fit the available holes in the toyo hood frame (or just drill your own).

Another idea is to get the silver backed high temp insulation that is used to wrap stove hood vents . It is aceramic spun insulation that works for heat as well as sound. It won't collect/hold water/moisture either and won't promote mold growth.