how to force shortened staff lines?

[Bric]

i want to generate a landscape score, but one where the staff lines 
extend some percentage of the printable area - let's say, 70%. Leaving 
30% width blank, on the right, for hand-written annotations (upon printout).

I've tried:

line-width = 70%

           ,

line-width = 7.0\in

      , and

right-margin = 3.0\in

but all that is being ignored.  At least in the "\paper {   }" block.

Help?