It will be interesting to see what others think. I would do what what you like best; after all you probably won't be driving it in the rain and snow year round, so I don't think it would rot your roof like before. I would be even more inclined to put it on if it was orignal to the car.
As...
FYI this is a 71 non-RT 340 Car. An RT would be a JS23 versus a JH23, which is a standard Challenger. In 1970 you could only get a 340 Challenger with the A66 package, which had all the RT bits, but was NOT an RT.
By the way they only made 41 of these JH cars in 1971 with a 3 speed.