[Richard]

Put the cowl insulation on and got the drivers firewall insulator in place. The molded plastic pieces are much nicer than the cardboard tar paper ones. The center section is left loose as I need to see if the engine harness will work going through the clutch rod hole, I think it will.
Both of the stock heater cores I had in hand were leakers. Went to the local radiator shop today and it is gone, the owner passed away. Found another in the valley and they had no interest in repairing.
The replacement core I purchased from Classic parts matched the thinner version of the cores (almost) so I was able to use those shorter mounting brackets.
Had no idea there were different cores? All set to put in now, new teflon lined heat-A/C control cables are on the way. Control and radio just put in to see.
Core on the right is the new one in the picture. I will probably try to repair the old cores myself at some time with some sil-floss brazing material. Used to braze copper all the time.