You don't have a TP/Wintec bucket do you? The steering shaft goes on the box then the column goes over the shaft with a bushing at the top. All that holds it all together is the where the base is welded to the column. If the lock nut comes loose the steering column can lift up and come off the steering box. How is yours held in place?
I have a u-joint that is splined on each end (both female). One end slides over the shaft coming out of the steering box and the male end of the column slides into the other. The reversed Corvair steering box probably isn't going to move, you know how those are fastened, and the steering column is firmly captured at the top and bottom, it isn't going anywhere either. I'm doing this from memory, but I believe that the whole affair is held together by 8 or 9 5/16" or 3/8" bolts. Three for the steering box, the rest to hold the column in place, and all go through either 1/4" aluminum plate or steel. To get all this apart the steering column is going to have to go up in the air at least 1 1/4", and that just can't happen without nearly destroying the car. Nevertheless, what I was trying to say earlier was not that the set screw(s) should be left out, but that if you want to be totally safe capturing the rest of the components well enough that this alone will do the job might be better.