Someone please correct me if I am wrong, but I am under the impression the 81 turbo distributor uses a Crank Angle Sensor that is mounted on the lower front of the block.
The 82 and 83 turbo has the CAS inside the distributor.
Are these dizzy's interchangeable?
If you removed the oil pump you will have to check the position of the "tang" on the oil pump drive shaft. With the engine at 0 degrees TDC, # 1 cylinder at the top of the compression stroke, both cam lobes pointing up, the offset "tang" should point to 11:25 o'clock. You can also place a screwdriver across the dizzy mounting surface on the block. With the screwdriver behind the top bolt and in front of the bottom bolt the "tang" should be parallel to the screwdriver.
You have to drop the oil pump to correct this, line the timing mark on the pump drive gear up with the oil squirt hole in the pump housing. Without moving the shaft slowly re-install the oil pump. Just before the drive gear touches the crank shaft rotate the oil pump one half of the diameter of the bolt hole in the pump clockwise. This compensates for the counter clockwise rotation of the shaft as the gears engage. This is easiest to do by placing one of the bolts in one of the pump holes, when the bolt touches the block rotate the pump clockwise push the pump in then rotate it back and screw in the bolt. Now check the "tang" alignment at the distributor mount hole with a screwdriver.
When you install the dizzy the rotor should be pointing approximately at 09:00 o'clock.
Wayne Monteath
Masham, Quebec.