I've taken quite a few '41 Cadillacs apart over the 56 years I've had them, and there has never been gasketing between paint and moldings. As mentoned previously, let new paint harden before installing trimming items.
Lemme say here, about the fender spears on all '41 Cadillacs, except the 60S. On the last one I had painted, I bought a set of the spears from McVey's for it (The convertible coupe). The original ones from production could never have been better than McVey's. They are magnificent, and fitted the holes perfectly. My painter should have put the black paint in the grooves, but must have forgotten, so I'll have to do it on some nice summer day. The set was 700 bucks, and I seriously doubt if the originals could ever be stripped and replated for that price......and come out so perfectly.
I plan on getting 2 more sets for the other two series 62 cars.