Design and build parameters change over the years from every maker, just because its 'old' doesn't mean its better. I have no idea how a 25 year old Century sofa was made, sorry.

Re-upholstery in my opinion, is done not for economical reasons, but because you have an enjoyment or bond with that particular piece and there is nothing on the market to replace it with. Either that, or if its a valuable old designer piece or important antique or heirloom. Old is Old. The springs are old, the webbing is tired, the cushions will be shot and the frame need to be re-bonded. Plus, the upholsterer has to make the patter from scratch. Costs a lot of money to do it right.

If you want the best upholstery in the USA, then Kindel, Karges, Councill is a pretty good place to go to. Be prepared to pay $ 10K for a sofa, however, and $ 6K for a chair. Taylor King is not at their level....