Check out the best position for the wires to come out of your dizzy, the clips to hold cap on and the vacumn 'appendage' (if you have left that on) in relation to the installation in your car. The physical dizzy body can go anywhere in the full 360 degree range but certain positions may be either impractical or more desirable for your installation (space is tight in these race cars!).
As long as you have a clearly marked TDC indication on your flywheel and mechanically time the cam shaft up to the TDC indicator in the cam wheel, then dropping the dizzy in is relatively easy.
The Bosch type have a mark on the body to line up with the mark in the end of the rotor arm and this sets the timing at factory (approx 10 degrees) which will get the engine running and allow you to use a strobe to set the far more aggressive race timing (35 -39 probably).
One image of the mark I found on the internet
http://i55.photobucket.com/albums/g132/ ... umber1.jpgSo if you have the engine at TDC and you know where you want the dizzy body to physically end up, you can drop it in, see where the rotor arm points (because of the bevelled gears the rotor shaft turns as you engage it), then lift it up slightly, move the rotor arm, drop it down again until it lines up roughly where you want. Then fine tune by moving the body.
I now remove the dizzy if taking an engine out and only put back into a fitted engine due to the constraints when fitting the engine back into the chassis
The rotor goes clockwise so if you want to set the dizzy closer to race spec then when you line up the marks you should then move the body anticlockwise to increase the advance. A difference of about 3-5mm between the physical mark and your new 'imagined' mark should get you right in the ball park eg manufacturer mark to the left (anti clock) 3-5mm from where your rotor arm is pointing - all at TDC). When you have got the engine fully race timed it is worth taking the cap off and making your own mark so you can return to this approx setting easily in the paddock during a panic re-time of the engine.