Making a four-on-the-tree, has anyone tried this?

From time to time, I've been known to sit and think about things that maybe don't need thinking about. Especially later at night, after a cocktail or two. Here's tonight's journey...

I have a 66 Valiant, slant and three on the tree that I intend to stay column shift if I can make it all work out. I'd like to have a 4-speed instead of the 3-speed. Clearly, the column shifter can handle four gears. I'm guessing it wouldn't know the difference between three forward with one reverse, and four forward gears. I'm thinking I could rig up some kind of cable mechanism for the reverse gear and tuck it up under the dash. That leaves the four shifter positions on the column for forward gears.

Has anyone tried this, and if so how did it turn out? If I'm the first to go down this rabbit hole, can anyone think of any good reasons why to attempt or avoid this business?

Enquiring minds want to know...:eek: