I should imagine that it might be of interest; I will circulate your offer to other owners of vintage boats.
1958 is perhaps the optimal year of build for cotton sails acquired now; the year in which terylene was introduced, so many owners who had just replaced their cotton sails subsequently upgraded to terylene; so a 1958 cotton sail may well have had very little actual use. If it has been well stored, as my ones have, if can be in beautiful condition.
Sorry I have not checked the Forum earlier, I usually get alerts of activity. The sail has been well stored and is clean but, when I got it out I see there are a couple of small amateur patches where I think the shroud has rubbed. It’s use is probably mainly to give an authentic appearance.