Is it really worth all the money and labour?
Thunderbirds aren't that rare. I'd wait for a better project to come along.
It's never worth the money, that's for sure. Nor is it worth the labour, assuming you're looking at labour expressed as time, even at minimum wage. But it's worth it for the sense of accomplishment and the sheer empowerment of "I did that!". I have restored from basket cases a Victory and a Ripper and neither will ever make a profit if sold, but that wasn't the point for me. It was the enjoyment of bringing poor, abused instruments back to something approaching their former glory.
If I wasn't a little tight for cash right now I'd have considered taking this project on.