Need Power Steering Shaft

Those plastic shear pins are there to keep the shaft from sliding around when being handled on the assembly line...they have zero effect on the columns ability to collapse or stay stable. Take one of these columns apart to see what I'm talking about.
Shortening the shaft to go from manual to power is no problem. There is PLENTY of room in there. Keep in mind that back in the day, when these cars were in normal service, the accepted proceedure when R&Ring steering boxes was to knock the roll pin out of the coupler, and then tap the shaft backwards into the column. Once the new box was in place, the shaft would get tapped back out and everything was good to go. This was done tens of thousands of times and nobody ever had an issue. I worked on these cars in the 70's and 80's and never thought twice about lenghtening or shortening column shafts...usually going from power to manual. It wasn't until the "Comic Book Guy's" got involved that it became taboo.