Oly how are your underlayments? The black tar sound deadening sheets. If they are intact and there is no rust under them go ahead and re-use them. They make a huge difference in sound and heat. After 55 years they get kind of brittle and when you try to remove them they break apart. The repops are pretty good, Dynamat is good, but since you are doing carpets you may as well go all the way. How are the floorboards? When I get done with them I always use a generous coating of POR-15 or other fine urethane sealer.