How to Fix Passenger Cowl Vent Seal Gap

FJRdoc said
I currently installing my restored non-AC heater box in my 1970 Duster.The box and blower motor installation went in without any problems. I installed the J bolt on the cowl and through the back of the heater box. After looking closely at the foam cowl seal, I noticed that it is gapping at the front. There isn't any way to clamp the seal and box to the front of the cowl. What's the easiest fix for this? Should I remove the box and add some additional sealing material on top of the cowl seal to help fill the void?

That's what I did (made a seal) out of black pipe insulation foam and attached it with 3M black and it worked great.
I also reinforced the J hook bracket to box on the inside with fiberglass so I could put a bit more pressure on it without tearing it out of the box wall.