How do I install a LA distributor in a Magnum?

Nope just drop it in anyway if it backfires flip it 180 the other way. Then adjust your timing. If the v-can is in the wrong way pull the drive gear out with a magnetic and adjust. Magnum motors have specific distributor gear, make sure to use what cam with and not mix parts just in case.

Why in hell do that when you can just as easily do it RIGHT THE FIRST TIME??

Either

1.....Pull the no1 plug, stick your finger in, bump the starter until you feel compression, bring the engine up to the timing marks where you want it timed, and drop it in or

2.....If the valve covers are off, bring it up to TDC and look at the no1 and no6 valves. Whichever pair is closed, that cylinder is ready to fire