Compressing Manual Steering Shaft to fit Power Steering?

A question posed to those who are wiser than me....

I am looking into converting my son's '68 Dart to power steering over the holidays. I have started looking for a power steering shaft to replace the manual shaft in the column, and a few people have suggested just tapping the end of the manual shaft up into the upper half with a hammer to make it fit. I know this will shear off the plastic shear pins inside the shaft, so my question is this... Once the shear pins have been broken, how does this affect the controlled collapse function of the steering column in a crash ?? Also, I read that once the shear pins have been broken, the lower shaft will want to slide down into the steering coupler and bottom out..what problems does that cause..?? As this car is my son's daily driver, if it reduces the safety of the column significantly I don't want to do it.

Educated opinions, anyone..??