My bike is a special const. title, it was that way when I bought it 23 years ago when insuring a bike wasn't a royal pain in the arse like now.That's good advice. Having a bike with a title is much better than building a special construction bike (SPCN). With SPCN bikes you can't get full coverage insurance. All you can get is liability and that won't cover your bike if it's stolen, wrecked, or any other sad story.
With the title you can at least replace the bikes value.
You can find full coverage all the way down to basic liability, but for full coverage/theft you're gonna pay $$$
Take the advice and get a donor that is titled as a HD or whatever make of bike you're wanting to build.