I've never heard of NADA, but when I had a claim on my '78 R80/7, Statefarm said they don't rely on KBB or similar, they do searches to see what similar bikes are selling for. (and my agent is my cousin so he wasn't lying;) ).
1978 BMW R80/7
"all we need is time and courage." - Renner
"A lightened flywheel on your bike is like me getting into Spandex and putting on track shoes to walk the dog." - M