Mr. Builder Bob,
The id plate only tells half of the story. The data card is where the real info is.
The third tab at the top of the page says Technical Manual - click on that, the 2nd item under contents is ID Tags. You can order an id tag from the Mercedes Classic Centre.
Have a good look at that page and links and you should be able to figure out everything. Just having the numbers sometimes doesn't say much - its where the numbers are on the data card that mean everything.
Once you figure out their meanings then you can look up the corresponding codes.
I think your tag says that
491 and 503 are option codes - US Version - Mirror on Left side
423H and 423 H are tobacco brown body and hard top colours 6 - Hardtop installed - soft top folded
113 (part of vin - model 113) 044 (280sl) 10 (left hand drive - manual tranny) 7 (? ) 11304410 should be first 8 numbers of your vin
0 60042 (??) 93732 (body number - number stamped into hood would be 3732)