ok, i had the 340 running great before taking the engine out.
We can read a LOT into that statement. HOW LONG was it out? (two years/ sour gas?)
What did you DO to the engine? (Different cam, out of time, etc valve adjustment?)
It should not take two DAYS to fix an ignition problem
THREE things needed to run
1. COMPRESSION: Do yo have compression? How do you know? You run a compression check?
2. FUEL Are you sure you are getting clean, fresh fuel?
3. SPARK meaning a GOOD enough spark and at the right TIME
Before you pull the dist. again, pull the coil wire from the COIL and use a probe to ground right at the top of the coil tower. Have someone crank the engine USING THE KEY. You should get a nice hot spark
ARE YOU SURE the timing marks are OK?
Remove no1 plug, and put a finger in the hole. Bump the engine until you START to feel compression. Now look at the marks and bump/ wrench the engine TO WHERE you want the timing, IE say, 10 before TDC.
Now check the dist or turn 180 so the rotor points to no1. RETARD the dist (cw for a sb) and then move the dist back ADVANCED (ccw for a sb) until the reluctor is pointing to the center of the pickup coil.
While you are at it, "spring" the rotor to be sure the mechanical advance is free
If it won't start and run at this setting, you have other problems, no spark, timing mark wrong, bad fuel, cam timing, etc.