Can you park the Soarer offroad? Then the classic insurance works just fine. You won't get much (if any) benefit from your existing NCD, and nor does classic insurance create new NCD, but classic insurance is so cheap it doesn't matter. The last one I had was a supercharged MR2 for about £110/year. Can't imagine the Soarer would be much more.
I've got far too many cars, and have had the dance with multicar insurance (not worth it, etc) for the last few years. Now each car has its own policy, some earn their own NCD, others don't.