Steering column questions

[NicoSlam]

So I'm in the process of installing a 700r4 in my 69SWB and have questions regarding what type of Steering Column to find. I was told that a 3 speed Auto column would work and only the indicator needs to be changed to a 4 speed. I mentioned to bowtieoverdrives that it didn't make sense since the pivot points at the bottom end may not allow that extra position. I was told that the overall throw was the same. I was convinced and ordered the 4 speed indicator by iditit. Now, I see 4 speed auto columns for sale so I'm confused as to there must be a reason why GM made two types of columns. Was I right about the pivots or can you use a 3 speed column as a four speed with simply changing the indicator?? On another thread discussing my trans, The point was made that there really is no need to be on the last gear select which I agree but I want to understand compatibility before I take the short cut.

thanks