Early mountain bikes offer a lot of possibilities for not much $$. Some are even lugged and lack the unicrown fork. Canti brakes and a chrome moly (sometimes oversized) steel frame, add Moustache, drop or porteur bars and substitute some smoother fat tires (Panaracer GravelKings?) for the knobby tires and you will be surprised by their "all road" ability. Pic is in Oregon, but I keep this one at our Florida place now. It's a late 80's Fisher HK II and you can get used to the unicrown fork. Don