There is no maximum number of dice you can roll - it is infinite as the rules never explicitly call out a maximum dice total.
Considering the mechanics of the game though the extreme theoretical limit would be somewhere over 70 (but likely less than 80).
I don't have the time to go through every card to work it out, but given the example ...
It's possible to houserule anything, and these cards aren't an exception.
Just have in mind that if you want to add these in using just the Dunwich Horror rules, it will decrease the game's difficulty considerably.
In the core game when your Sanity or Stamina drops to 0 you:
Discard half of your items
Discard half of your Clues
Recover 1 Sanity or Stamina