Brother bulldog1935 is the subject matter expert here, but I had two of the Condex reels on hand, which I have decided to gift to a couple of nephews. For these boys, I wanted to convert to LHW.
As bulldog has explained before, the greatest difficulty arises from the fact that the spring in the Condex is not readily removed. You may get it out and back into place, but any subtle adjustments you have made to the spring will be lost in the process. I found I could not adjust the spring to my liking with it in place, so I chose a different method. I drilled out the riveted stud which retains the spring. On the lathe, I turned a duplicate of this stud, but with a No. 4-40 thread as opposed to a stem designed to be riveted. I knew it would take me a few iterations to get the spring tuned correctly, so my spring retainer needed to be removable.
Next, using dividers, I located the new spring attachment point (opposite to the original), and driiled and tapped to No. 4-40. From here it was easy - install the spring and stud, test, and remove to adjust as required. For the final installation, I placed a drop of varnish on the threads of the stud to help keep it from wandering.
I'm happy with the outcome. One reel is exactly as I would want it, the other is quite acceptable, but I may go back and "tweak" it just a bit more. I know the boys will be happy with these fine old reels and with the new fly rods I will be giving them.