Zoomcat
If you have a dished rear sprocket with offset rim,install with concave side out.
That is with teeth furthest from the hub.If chain then is hitting fork try spacing fork out with washers.Installing and removing sprockets goes alot quicker if you chuck a socket with drive in a cordless drill.Make sure sprocket is not tilted but in a parallel plane with tire.If tire is running true take spring clamp and clamp a popsicle stick or similar to fork barely touching sprocket and turn wheel to see if sprocket is running true.Tighten bolts where its running out.Ron