Thanks for your thoughts, guys! The maker of my harp is William MacDonald, of Skye. It’s his 30 string Scathach model.
Having considered what you’ve said above, I will probably leave it as original, as it is really a lovely
harp! There’s a short video of it on William’s YouTube channel.
It doesn’t have bridge pins or enough space for levers. So as you suggest, might be more sensible to buy a nylon string! And maybe try ways of playing wire without nails.
Thanks again for your helpful replies!