Fuel line and exhaust question for rear tank installation

[Jayschevy]

How close can I run a fuel line to my exhaust and be safe? A few months back I raised my dual exhaust and ran it through my carrier bearing crossmember because I bagged my truck. This weekend I plan to add a rear gas tank on my 71. I'm planning on runing the fuel hose down the passinger side of the frame along the inside wall of the frame. This would put the fuel hose about 6 to 8 inches from my exhaust pipe. Is this a good enough distance not to cause any safety concerns? How are you guys with rear gas tanks running your fuel lines?