I am having a similar dilema, I am painting my duster now and didn't know what to do with the cowl. My solution was to pull the heater box and vent out and I pulled in a towel and spread it out to cover the original paint, to not get overspray etc in there. This is fine for the car I am doing as the original paint/primer is in good condition. On my other Duster this is not the case, there is much overspray from previous paintjobs(and colors). I wonder how the high end resto shops deal with this? Somebody must know....