We just bought a 4500 square foot ranch built in 1940. Most of the current flooring is carpet over concrete. Can we use regular hardwood flooring rather than engineered? What type of underlayment should we use? Our ceilings are 8 ft. tall, therefore plywood seems to raise the level of the floor too much. In addition, we would love to install radiant heat under the hardwood if possible. Any thoughts or suggestions?