If you have the non auto advance type (you use your spark rod to advance the timing), just use the timing pin in the front cover to set TDC.
Then just snug the cam screw so you still can turn the cam. Install rotor and dist body and turn the rotor so that the left edge of the brass tab on the rotor is oppsite the #1 pin in the dist body. Carefully remove rotor and tight cam screw using a cam wrench so it doesn't move.
This will get you in the ball park. Take the car for a drive and see how you like it. You may have to reset the timing slightly, but I doubt it.
If you have the auto advance type best to call FSI for help, they are very helpful.
I have the non auto type on my 31 pickup and love it.
Regards,
herb