What do I know---I'm just an old man
I'll try to help you out just a little bit. The DT stands for Double taper,means the line is the same on both ends. So when one end wears ont you can just turn it around and use the other end. F stands for floating. The HCH I think stands for the weight in grains,but I'm not sure.
It is better to go up a line size than go down a size. So you would be better off going with a weight foward 6 or a DT 7.
Just one more question. What are you going to use the bigger rod for?