I have a stock 289 in a '67 that I'd like to swap the distributor. I've heard some issues with the oil pump rod being displaced or even possibly falling into the oil pan. Anyone have any issues with this?

 

If the oil pump drive rod is as it was from the factory, there is a retaining clip on the oil pump drive rod below the perch the distributor drive gear rests. If the drive rod is stuck in the bottom of the distributor, the clip can slip, allowing the drive rod to lift with the distributor. If it does it can then fall into the oil pan. If the retaining clip is not present, the probability of that happening is much greater. When the retaining clip is present, the chance of it happening is there, but slight. I've pulled several, maybe 20, I've had the drive rod fall into the pan once. Twice I've had the drive rod come out of the oil pump twice, but not fall into the pan. In those cases, I used a small round magnet on a reach rod to pick it up and put it back into the oil pump. If your motor is clean on the inside, no caked/burnt oil, I don't think I would be too worried about it.