If it's the dist... That can't really be fixed, even tomj says so, he has detailed write up's about it, he did say..... 

"A pertronix module seems to lessen the effect of a worn distributor shaft bushing, and certainly slows or stops future wear, since there are no longer the spring-loaded points pressing sideways on the end of the shaft." 

You could very well have a cracked head causing the misfire. I hate to mention that, but I had that issue years ago. The only way to know for sure is to take the head off and have is magna-fluxed to check for cracks. I wouldn't do that at this point. I drove mine for 2-3 years with a "wandering mis" at idle. At higher speeds it wasn't detectable (to ear or felt driving), and seemed to get better as the car warmed up (but never totally went away). I wrote it off as distributor wear. I've recounted the story where I drove the car cross country and the cracks opened up the third day of driving -- kind of hard on it with long days and pulling a utility trailer.

So what I'd do if this were my car:

1) Install a Pertronix Ignitor II to make sure it's not a points/condensor or distributor lobe wear issue.

2) If that doesn't help use a block sealer product such as K&W Block Seal. I've used this before with good results, just make sure you follow directions! Won't clog radiator. I used it on a early 2000s Daewoo that my daughter had. Thought it had a cracked head, used the block seal while I tried to locate a used head. Ran it like that for 3-4 months, daily driven, no issues. I finally located a head, but my brother suggested we pull it and make sure that's the issue first -- wouldn't want to buy a head and discover it's the block or something. Turned out it was just a bad head gasket -- but the block seal sealed it pretty darned good! Won't hurt to run the sealer through it even if there isn't an issue.  You don't leave the sealer in -- have to drain and flush the cooling system before (won't work with anti-freeze in system) and after.

Put a vacuum gauge on the engine. Google "vacuum gauge diagnosis", study the chart & compare your readings.

Doing this will help to narrow down the cause of your miss.

the best way to describe it is to think of it as a camshaft and lifter.

look at the distributor where the points contact the shaft.  you will see 8 flat spots (for a v8) and 8 sharp lobes.  as the distributor turns, the lobes open the points.  thats like the lifter opening the valve. 

the dwell is the setting as to, how close the points are to the shaft.  the closer you are,  the faster the points will open.  the farther away,  the points open later. 

the points setting determines the amount of power that will be sent to the coil.  (amount of spark you get)

the dwell setting determines when it will be sent. 

these adjustments should be done before timing the vehicle.

hope this helps.