Length?
I have
267mm
280mm (stock vmax rear)
298mm
320mm
The Venture rears have an offset in them though (I think they are 298mm) so nothing else will fit that I know of. Know, you could do the 320mm and simply use spacers to achieve the same offset you need.
Working on a project, fitting a 2000 venture swingarm on a 1986 vmax. Using the vmax wheel and venture brake caliper on the swingarm. The rotor on the 2000 has way different holes and the center is bigger. That's why I was wondering about the first gen rotor.