Welcome Jorgen,
Good luck with your search for one of the finest cars ever made by MB
I purchased one just over 2 weeks ago and made a careful check list. Perhaps you like to use it or add to it. See below ... Mind you some of the info may not be available, at least it gives you a start
Initial Check List for 1969 Mercedes 280 SLWRITE DOWN FULL DETAILS SUCH AS;
VIN # _____________________________
ENGINE #__________________________
TRANSMISSION ____________________
OPTIONS _____________________________________________________
VERYFY NUMBERS WITH CURRENT REGISTRATION ____
CHECK AND NOTE LAST EMISSION INSP. __________________
COLOUR CODE _________________
KEY CHECK (ALL DOORS AND TRUNK SAME KEY) ________________ (not always the case)
CHECK HEATER IF IT WORKS ____ (Repair is costly).
CHECK ALL CROME PIECES ____ (Grill alone is $3K Bumpers are also very expensive).
CHECK HOOD, DOORS, TRUNK AND SOFT TOP COVER FOR DENTS, ALL THOSE COMPONENTS ARE ALUMINIUM AND DENT VERY EASEALY.
CHECK UNDER ALL CARPETS FOR RUST (front loors, rear floors, if possible lift up rear wood bench also check the trunk rubber mat).
CHECK REAR PANELS UNDER BUMPERS AND LICENCE PLATE FOR RUST (they are doubble skined and trap moisture).
CHECK WIPERS TO MAKE SURE THEY WORK (it is time consuming to repair also costly).
CHECK FOR ACCIDENT DAMAGE (lift hood and trunk the factory tack welds should be clearly visable also below the car - if not then the car was in an acident).
CHECK ENGINE OIL AND FOR EXCESSIVE GAS SMELL ___
CHECK TRANSMISSION FLUID (should be bright to dull red ~ black spells trouble).
CHECK COOLING SYSTEM RESERVOIR (colour should be fresh green or yellow)
CHECK GAS FILLER AREA FOR RUST ___
ONCE ENGINE IS UP TO OPERATING TEMP. LISTEN FOR NOISES FROM VALVES AND TIMING CHAIN (rattles or knocks).
CHECK FOR SMOKE FROM EXHAUST AT LOW AND IDLE SPEED (puff of blue smoke for a moment is acceptable, however continues blue is bad). White smoke means the head gasket is blown.
INSPECT THE UNDERSIDE OF THE CAR (look for oil leaks, road damage, rust and take pictures) ____
GET PERMISSION TO HAVE CAR INSPECTED (you pay for the inspection - it will provide insight as to what repairs if any are to be done in the near future)
DRIVE THE CAR (check items listed below during the test drive) ____
CHECK SUSPENSION (for clunks, rattles or odd noises) _____
CHECK TRANSMISSION (for noises, clunking, slippage or squeals) ____
CHECK FOR SMOOTH GEAR CHANGE (or jearcks bad) ____
STEERING WHEEL (easy to turn or clunking (clunk means the rubber isolator or linkage is bad)____
CHECK ALIGNMENT (stear true and straight) ____
BREAKES (do they pull evenly or to one side) ____
PARKING BRAKE (coast to stop and pull the brake)____
BRAKE PEDAL FEEL IS FIRM OR SPONNGY (not firm then problem with system) ___
REVIEW PAST INSPECTION REPORTS ___ IF THERE IS NO CARFAX REPORT (US and Canada) WHEN CAR WAS PURCHASED THE CAR THEN PULL A REPORT FROM THE INTERNET.
MAKE AN OFFER TO PURCHASE THE CAR.