When I was working on the passenger side inner cowl of my truck (1953 3100), I made a crude adapter for a small cowl vent. The opening is actually for the optional fresh air heater, which I do not have. So, instead of just putting the block off plate in the truck, I got a used, small vent (can't remember the make or model of car it came from) cut some sheet metal stock and made my adapter. It fits in the truck and the vent will work just fine. My point is that you might be able to do something similar if the cost of replacements is too much. Just a thought.
