One way I've swapped distributors and avoided the need for a timing light is to align the pickup points on the distributor. If you have an original distributor with the upright thingies, I bring the rotor around toward the #1 plug and align the pickup points perfectly. I then mark the pickup point and the position of the rotor with a magic marker. When I set the new distributor in, I set it up to match the old one. It works the same way with the newer star type pickup points.
Aligning the pickup points is very easy on a manual trans car. The ignition coil lead can be pulled and the starter bumped to bring th rotor around toward the #1 position. The car should be on a level surface, as you are inside your building. I then place the trans in 3rd or 4th gear and gently nudge the car forward until the points align. If you go past an alignment point, back up well past it then try again. The engine should always be going in the direction of rotation to take up cam chain slack.