You will probably get more definitive responses from others in the forum. But there are no guarantees the outside trunk badging is accurate on any of these cars.
In Germany, where the numbers and letters have had more meaning to the average motorist than here, the US models that came out in the early 70's with the 450SL and 450SE or SEL designators on the trunk on European Delivery caused some engine displacement envy.
To address this replacement badges with the higher displacement indicators were hot items for a while. On the other hand, there were, I believe, US models with 350SL/SE/SEL badges for European delivery, that had the 4.5 liter engines, and they were rebadged by the dealer with the 450SL/SE/SEL badges as appropriate when they were serviced in this country.
Rebadging in this country is nothing new either, as you can find Ford, Nissans, Hondas and Toyotas with badges from various MB models. So, you may have a car labelled 450SE, that came from Germany with a German market 3.5 liter engine of that era installed.
Sounds like a stretch, but if you have the actual engine number off the block and it is from a 3.5 liter engine, I would conclude your engine is a 3.5 liter engine. Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)