I am buying a 1950s co-op which has a pre-war feel. I love the unit and don't plan on any renovations except the interior doors. Currently, it has raised, 4-panel interior doors, which look new. The doors also have that the horrible, brass, ornate, shiny, l-shaped handles. I want solid, old, single panel doors. Are they hard to find?...expensive?....hard to restore and install?