I'm looking to do the same thing on my 07 train. Would like to bring the bars in a couple inches. Got the 3" extensions on the controls with no problem, but my arms must not be proportional to my legs. Not too bad unless I am riding for a few hours straight.
A friend of mine has a 08 night train with straight up risers and drag bars. We are going to put the curved risers and duece bars on his bike. We can use the existing cables and brake line.
easiest would be to change the raisers so that they give you the pull back that you are looking for, that should normally work with the cables you have now.
Yes you can use the stock cables... I ran a 9" rise 3" pull t-bars with out a prob.
I would skip the duece risers... Why not save a little coin then just go with some T drag bars with some pull back... then you can run the wires inside, it'll look a lot cleaner but thats just my 2 cents... but you will have to lengthen the wires, but it's worth it!