I've no idea why Jim mentioned castrati at all, and if there was any reason why Western-trained ones should be more relevant it was lost in that mass of unreadably formatted verbiage.

The point about the hijras is that they're around now, easy to locate, and sing in a wide range of styles with varying levels and types of training. If you want to find out what the capabilities of the castrato voice are, they're a far more informative resource than Moreschi's 78s.