I also had 1966 Twinco for 8 years, which I sold two years ago. $5 avgas means $70-80 an hour for fuel at 14-16 gph, and insurance runs $2500-3500 annually for decent coverage. It doesn't leave much, if anything, for maintenance if you're charging less than $180 based on 150 hours annually. I suppose you could go liability only and roll the dice that you don't have a gear incident with some rookie time builder. Not a chance I'd want to take.