Correct procedure (angle mount distributors only):
1) Slide timing tab over right hand side of clutch housing to reveal the flywheel.
2) Ignition switch OFF, manually turn engine over and align the pointer inside the timing tab hole to 4% BTDC.
3) Your distributor has a little oiling port on its side. That should face about 90% away from the engine when installed. Place dist cap on distributor (it should only go on one way) and mark (grease pencil) the distributor where the #1 plug wire goes into the cap (it should be marked "1" on the cap). Remove cap.
Looking at the distributor facing THAT WAY (i.e., looking perpendicular to engine with oil port towards you) rotate rotor to about 10% more toward you than the mark on the cap. Insert distributor into dist hole. As it goes in, the distributor will spin (caused by eccentric gears on distributor). If you are lucky, it will spin exactly to your mark on the distributor. If not, pull it back out and keep trying until it does.
4) Lock the distributor into postion, regap/replace points, condensor, etc, replace cap and put your #1 plug wire in the #1 cap port. Firing order is 1-2-4-3 CCW.