candres 41 - it looks like a "mixed set": SLX frame (Corsa Extra), SL fork (Professional/Corsa) - rebuilt and repainted...
Mackers - chrome plating of the whole rear triangle was an option available to everyone; EMC performed such orders very rarely before 1990 in frames built with 753 and 653 (in both models the rear triangle was made of ...753 - a material very difficult to chrome plating). Since 1990 they did it without any problem ... But the 653 frames were no longer produced and the 753 were built in very short series.
If the chrome is in good condition, the frame may be chrome plated and painted on the same occasion.