Almost all my routes have plenty of premium demand, so the backbone of my fleet consists of Lockheed Super Constellations in 70Y, 8C configuration. It gets me around $1500 more per route than if I'd filled the plane with Y seating. The Comet 3s I'm putting into service at the moment have 60 Y seats and 3 C seats each, as they're smaller and their speed allows them to fly routes more frequently (hence scooping up the rest of C demand).
My advice is that a large bird like a DC6 should definitely have some C seats on longer routes. If the lease is running for a couple more years you'll be very glad you took it out of service for 3 days!