Advice needed for updating heating

Hello all, I noticed my oil tank (old and rusty) is starting to sweat oil on the bottom. Not actively leaking on the floor yet but knew its time to get it replaced. My furnace is also 30years old and im concerned about it failing when I need it most. Having a hard time deciding whether to replace the tank and get a new furnace or take the opportunity while the tank is getting changed to make the switch to propane. I live in CT if that affects anything. Any advice would be appreciated!