See if this post helps you.
Distributor Install Help

I did a quick search (top right of page) for "installing distributor" there's a full page of results, it's been written about many times.

I think you're 180 degrees out. remember the crank rotates twice to the distributor rotating once. So you must verify that #1 cylinder is on the compression stroke.
easiest way to do that (for me) is to pull the spark plug from the head and have someone "bump" the starter while holding my finger over the plug hole.
When I feel the air pushing out, stop and manually turn the crank to align the timing marks, then install the dizzy in the desired position. If it won't drop in, I use a large long screwdriver to align the oil pump so the dizzy falls in. You can see the slot when looking into the motor, turn it slightly and try to drop the dizzy in. Some guys like to turn the motor back or forward, I just found it easier to spin the pump connection to where I needed it.