I used the string and jack stand method after installing a lot of front end parts on my 89 244. The front and rear track are way different, true, BUT by carefully making each side's string parallel to the other side, using a tape measure to the center of the wheels, you can get parellelism, your distance from center of hub to string will be greater at the back than in the front (the front has a wider track). This takes a good deal of time and patience, but can be done. Then you go about measuring front toe. You can be accurate and you while benefit from having a helper help you measure across the car from underneath. From a bar placed at an angle (top of the tire angled down to the bottom of the tire, avoiding the bulge in the tire). Make sure all your tires have equal pressure in them as well. I drove my car for several weeks this way before having a computer alignment done (I didn't want to ruin my brand new tires). I did drive well after my string alignment, but not 100% spot on.
Charles