Early falcons use a 1 piece steering box/shaft combo. You would have to cut the shaft off close to the box, re-spline or grind it into a "D" shape and then connect it to a shorter collapsible shaft/column with a u-joint. Quite a bit of work.
I installed a column from a 69 Mustang and used the rag joint. The column shaft is in two sections inside the column; one slides in the other. I since went to R&P with the universals, but kept the same column. So to answer your question, yes you can install a different column. Just a little fabricating.
add: the late 67 Mustang steering box has the 1-1/8 sector shaft which is the same as 64 and earlier Falcons and uses the rag joint.
Mustangs didn't have column shifts that I can remember, so you will probably have to go to floor shift. Or you could cut you shaft and weld a coupler and or use a u-joint type setup and a box with short input shaft.
The shifter is part of the column cover,not the shaft.I just did a four speed conversion on a Falcon that originally had a three speed,used a column cover from a 4-speed 65 Comet.An engineer once said that if you are worried about being speared by the column,quit driving!!!If you get hit hard enough to drive the entire front end,clear back to the firewall,back into the drivers compartment,you probably died from a multitude of issues!!!!A column can only collapse so far,usually about 1-2 inches!! JMO,ROY.