My 94 K75 has a drip leak from the fuel tank overflow tube about the rate of an ounce per 8 hours. My suspicion is that there is a pin hole in the line somewhere in the tank that allows fuel to enter it. Has anyone experienced this? I'm thinking that if I plug the overflow hose at the exit of the tank, it shouldn't be a problem. Is there something I am missing in this thinking?

You will need to find and fix the problem because just blocking the overflow line will likely cause you problems with a vacuum forming in the tank and fuel flow will be limited. The pump will pump big pressure and could cause the tank to cave in before the engine staves for fuel.

Rick,
 I was afraid of that answer.
 I wonder if I can apply compressed air to the outlet and feel for a leak in the tank line (empty of course)? 
Any suggestions are appreciated.

First thing comes to mind is whether it leaks all the time, or only when the fuel is above a certain level.  That might help identify what part of the tank you need to concentrate on. 

The problem with finding the leak with air pressure is that the line is not an overflow, but the tank vent, and it connects to the "burrito" in the upper part of the tank.  The "burrito" has several openings to allow air and some fuel to enter and leave it.  Obviously, these holes will make it difficult to spot an air leak in the tube. 

As far as the probable location of the leak, the first place to look is the spot where the tube exits the tank.  Corrosion or a broken weld could cause your problem.  Fortunately, that would be the easiest to repair.  I really doubt that there is a hole in the tube as I can't imagine a way to make one where the tube runs in the tank. 

It is also remotely possible that the problem is a bad o-ring in the plate that holds the fuel level sensor.  There's a slight chance that the tank insulation is guiding the leaking fuel from the plate to the spot where the vent spigot is located.

.75
Thanks for the insights. I verified that it is in fact coming out the overflow. I agree that the likely trouble spot is at the exit. 
I have used a two part epoxy (like chewing gum) on the outside with good results. What would you recommend as a sealer for the inside?

Make very sure that's where the leak is first. 

Personally, I am reluctant to put any kind of sealer or coating inside a fuel tank.  Gasoline and ethanol(especially that damn ethanol) are powerful solvents that seem to turn anything I put in the tank to goo floating around with the fuel.

I would just be very sure that the spot where I putting the patch was a perfectly clean as I could get it.  Remove all the paint and wash the area a couple times with rubbing alcohol.  JB Weld makes an excellent tank sealant that many have used with good results.