I'm not sure. A lot of people do suburi, but they dont have internal strenght. Is there something like six directions, silk reeling in suburi?
For me, some of the specifics are in Budds replies already.
Opening & closing.
6 directions would always be a constant whether doing weapons or not.
I don't see Bowing excercise mentioned...arguably its covered by open/close anyway.
But unless you have some reference points ....you'll just be doing same old suburi ...what Keith said really.
I guess your next move could be to mine in on the specifics of opening & closing and bowing ....if you can find out more on these then that will help.
Maybe someone a bit more eloquent ....and willing.......... than me will provide some descriptions although they are probably here in abundance in some of the historic posts.