So do you guys think I should put some sort of foam to close out this area ?
Yes.....closed cell (wetsuit-like density) to prevent high pressure (fan forced) air under hood going to low pressure area in front of radiator when stationary.
While you're at it......open up the core support rad attach holes and install grommets to prevent twist in the panel from tearing up your tank ends. Existing bolts and washers but need nylon nuts.
Also a ground wire to the rad to prevent internal corrosion from electrical charge in coolant.