well...there are a couple of possibilities:
1) the car is an evoI with the wrong valve cover/engine
2) the car is a 2.3-16 with an evoI body kit on it

since that car is registered as an '85, i would say that it is the latter. hydropneumatic shocks may have been available at all corners in europe at that time. just not for north america.
since you paid only $7000 for it (i am assuming US exchange) i would say that it is a modified 2.3-16. and no, you didn't pay too much for it. :-)

the best way to determine the model of any car that you, or anyone else, might question is to get the VIN number and take it to the nearest Mercedes-Benz factory dealer. they'll be able to look up the vin number and come up with a positive ID on almost any M-B

cheers!

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'94 W124.036 249/040 leder; 8.25x17 EvoIIs
'93 W124.036 199/040 leder; 8.25x17 EvoIIs, up in flames...LITERALLY!
'93 W124.036 481/040 leder; euro delivery; 8.25x17 EvoIIs
'88 R107.048 441/409 leder; Euro lights
'87 W201.034 199/040 leder; Euro lights; EvoII brakes; 8x16 EvoIs - soon: 500E rear brakes
'70 R113.044 050/526; factory alloys; Euro lights