Lotus Supplies sells replacement brackets. I'd imagine that r.d. enterprises, Dave Bean, and other Brit suppliers do as well.
I understand wanting to keep your car as stock as possible but I'm not one of those people so my opinion might be suspect. aI think there are some mods that are acceptable to even the "keep it original" crowd and I think adjustable lower links are one of them. I'm not saying, "Don't be a dope, just get adjustable links." I am just saying that they are worth considering even if you want to keep your car "original." On the other hand, a new bracket is surely less expensive than a set of adjustable links!
Maybe someone who is more in tune with the keep it original crowd can correct me if I'm mistaken.