There is no such thing as mounting points on the Valk, no lower frame work..what you need is a need is a frame that attaches to the upper frame...the only ones I know that made that frame was a sidecar company in Washington state called Dauntless Sidecar, at the time I was checking it out the frame cost around $1000 bucks, that was 10 years ago..here's the website.
www.dmcsidecars.com