It did have a custom setting where you could choose your neck length (standard is 540mm it suggested)

There is a formula at Tensions if your maths is good - which I'm guessing it might be.

As some asides...

I made a string gauge calculator that worked as I wanted it to as a friend was a big "open C put piano strings on" and wondered why he took it back to the menders.

Most instruments don't say what the overall force should be. A friend has a very expensive, very old Martin guitar which no longer gets played outside of the house (which he once lent me for a few days when I was visiting - no greater love etc etc) which has a VERY specific instruction NOT to put strings over a certain weight on.

But as far as I can see stringed instrument manufacturers recommend a weight of string but not really giving the range where damage may occur. I did check a few sites and don't think they state it really.

The first guitar I had was a £10 Tatra classical and I think they said 'do not put steel strings on this or...' but that is about it

I have a friend I play with who is happy with adjusting truss rods etc who has given me a little more confidence to experiment. But also to see the difference that different sets of strings make to the action and playability of the guitar

Mind you, I don't think whistle manufacturers tell you what is the hardest you can blow.