As Racerone said, set top cylinder to TDC with a dial pointer or caliper. Now remove distributor pully cover and see where cast arrow points. Remove timing belt if necessary to make arrow point to TDC dot on flywheel decal.
Now remove rest of spark plugs. install top spark plug into engine and install spark plug wire to it. Ground balance of spark plug wires, to block. Remove prop.
Idle Pickup Timing: Set throttle such that the carbs are ready to open, but still closed. With ignition on and timing light on top cylinder, jumper starter solenoid and read timing on decal, at timing pointer or timing mark.
Idle Pickup timing should be 4-6* BTDC. Loosen two vertical bolts on distributor collar and adjust distributor "swing" to make it read correct timing. You may need to adjust throttle cable as well.
Set throttle to full. Crank motor and read timing it should be 21*BTDC. Adjust max spark advance set screw above distributor to make it so.
Adjust throttle stop set screw to allow carbs to open fully, but no more.
Loosen idle stop screw for now. When you set final idle speed, tighten screw to lock in minimum idle speed.
