In addition to the great advice already submitted, try a new starter cable. The CA175 cable like
http://www.ebay.com/itm/Honda-CA175K...1b7eb6&vxp=mtr
The CA175 cable works well, but a bit long, so you would need to curl the excess in the frame body. Or have a duplicate new cable fabricated. I contend that 45-50 year old copper cable and connections just degrade, especially our barn find bikes.