I am not advertising for this ebay seller. Just pointing out a great source for old style solo seats that you can adapt to many kinds of bike you rebuild. I have two of these seats myself. Nice steel pans. Copies of 50's Harley police seats. Nice firm padding and a good leather cover. Only bad thing I can say is the leather on both of mine was very dry. Would have crumbled if I didn't treat it. But a few applications of a good leather oil and they are good to go again. Just treat before use to prevent damaging leather fibers.
Link to one for sale. (I have one identical to this plus a brown one. Very nice for this price range. I have one on my RE and am adapting the other to my Cali III.)http://www.ebay.com/itm/NEW-100-PURE-LEATHER-ROYAL-ENFIELD-CLASSIC-FRONT-SOLO-SADDLE-SEAT-TAN-COLOUR-/172632333632?hash=item2831b05d40:g:JiIAAOSwawpXqt4Y&vxp=mtr