No. Why would anyone at this point, when Swiss 55x are being imported.
The 540 receiver is also different than the 550, in several ways. There is no outward bump for the rubber dust covers. The bolt catch assembly is part of the upper.
Where are you planning on finding a 540 parts kit? There was an importer of the Chilean FAMAE 540 series, but they didn’t really bring in any significant quantities of semis. They were selling post-86 DS MGs, so maybe you could find someone who’s willing to cut their gun into a kit.