Re: firing order on a 258
If the distributor is firinng 180 degrees out the spark event will be happening on or about TDC of the exhaust stroke instead of the compression stroke. also some engines the distributor must be installed absolutely correctly for proper operation due to uneven firing orders, examples: 90 degree V6s, air cooled volkswagens....
Also an easy way to remember I6 firing order: Too young, Too old, Just right, 15,36,24 dirty old men think these things up.
good luck, jjc