A local outfit is letting me take a NA 310 for a 10-day family trip. Legacy avionics with the obligatory moving map. It has been phased out of their training fleet in favor of a Seminole. They expect some compensation but they've left that for me to calculate.

What's a reasonable dry rate for a purely pt91 non-turbo '67 310L these days?

I’ll put a number out there… $175/hr dry considering the details (age/make/model/equipment) of the plane you are attempting to rent, and I’ll let others comment. Just taking a swag at a number, although there a plenty of unmentioned variables to consider. You can figure it will cost you about $200/hr +/- for fuel, depending on fuel prices.

Just my personal opinion as I have pondered being on both sides of this equation (feel free to agree or disagree):

If this is a low volume arrangement between acquaintances, which it sounds like it is, my number is 2-2.5x of the reserve rate.

If it is a higher volume usage, to the point where maintenance schedules hasten and/or wear and tear becomes a real concern, or taking effort to
manage the arrangement, say 3X+ the reserve rate.

It's a low volume deal. I like that rule of thumb. It yields a number pretty close to what Mike recommended as well.

Thanks!