When I went to PCS to get an 18" Comstar wheel for the new frame I took my tape measure. The measurements I took are only approximate but might help someone else who is trying to do something like this.
Track width: approx. 44"-45"
Sidecar wheel lead: approx. 8"-9", but this isn't really helpful because there were only 2WD outfits available to measure and I found a reference on the web that mentioned that 1WD Urals have greater lead than 2WD Urals.
I would still like to hear from someone who has a 1WD Ural about this.
BTW: The mechanic I spoke to told me that Ural has re-designed the sidecar frame for 2011. I didn't take pics, but basically the frame is no longer flat but has a dip in the lengthwise members to clear the sidecar driveshaft so that the sidecar body for the 2WD models does not have to sit so high above the frame at the back.
The nut for the sidecar axle is available from UC/PCS for $5.55. Since I was already there I bought one rather than taking a chance on getting what I needed at Brafasco.
Swingarm bolt torque: The mechanic told me that there is no specified torque for these bolts so they just do them up with appropriate torque for that size bolt. I mentioned that Honda manuals have a table of standard torque values for various fastener sizes and he said if I wanted to bother with a torque spec it should be OK to use what Honda recommends for that size bolt. Honda says 50-60 Nm for 12mm bolts/nuts and nearer to the higher end of the spec for flange bolts/nuts.
I have decided to replace the 12mm flange bolts & nuts that came with my frame with 1/2-13x3" bolts with elastic stop nuts and washers because the 1/2" (nom. 12.7mm) bolts will fit easily through the existing holes in the frame and the rubber bushings with much less slop than the 12mm bolts.