Factory A/C in 1967-1972 Darts

My car was garage kept by the first owner and carport kept by the second.
I had my hands down the vent stack as far as it could go before painting and there was minimal debris.

The evaporator case did leak when I got it but it was because the gasket was folded, causing it to have a gap. I fixed that and applied a very thin amount of clear silicone sealer at reassembly.
I also filed the gasket where the drain to the firewall goes from the inner box to the outer because I noticed it was particularly high there, causing the condensate to reach a high level on that side before it could overcome the gasket and exit via the drain.

I noticed no debris while I had the box open.

You can clearly see small droplets form on the outside of the evap box after about 20 minutes of operating.
It never freezes up, but the droplets move on any turn, and combine to form drops which then land on the floor.