Kevin - a 63 year-old memory is a dangerous thing but if I remember correctly, in looking at the insulation strips that ERA installs, the area towards the upper part of the cowl or fender behind the firewall and just above the level of the hinges appeared to be the least well sealed. So that is probably where the heat is coming from. But I think you can block most of it off from behind the door hinge area.
I bet that heat felt a lot better in the winter than it does now.
Dan