Curious if you ever got an answer to this one. In a similar situation now. Would think if you bought stock in NewCo, which then bought the OldCo you would qualify for Qsbs when you sold NewCo.

Definitely talk to a tax lawyer because I think there are a few issues you are likely to encounter. If you're asking about the shares of the operating company, I believe the shares have to be original issue shares from the company to qualify. If you're asking about the newco shares, there are requirements around being engaged in an active trade or business, so if it's a holdco i don't know if this will work. But these are all general principles and you have to talk to an expert, I wouldn't try and research it yourself.