Manual s.box in a 66,with 360

I,m installing a manual s.box in my 66 Dart and am swapping the 6 cyl. with p.steering to a 360 with manual s. bow.I have a floor shift steering column and another member was mentioning that I would have to lenghthen the shaft from column to box.Is this true?I haven,t measured this yet,but if someone has done this?Did you have to add to the shaft?Thanks for any insight on lengthening!