Just to be clear - my 6542 project is based on the 1030, not the 1530, which uses a different set of GMT-related parts.
As I have discovered, GMT conversion is not a simple process of swapping parts out (for starters, the 1030 was made with (at least) 3 different pillar plates). And, as I discovered, locating the missing GMT parts for these older movements (these parts are often not shared with other non-GMT watches of the same vintage, which leaves a very small gene pool from which to find spares) can be a frustrating experience with unavoidable dead ends & false starts. There are few shortcuts. You have to be VERY patient, aggressive & single-minded in your parts search.