It can be challenging to find a round guarded super blackhawk trigger guard.
They used to run around a hundred bucks.
There is a LOT of fitting involved. they come from the factory rough cast on the outside.
A direct swap is not likely as each trigger guard is mated and fitted to a specific frame, and the frames are all different sizes.
A competent gunsmith could probably cut, reshape, and tig weld your current trigger guard for about the same price.