Borgeson Power Steering Thoughts....
I recall reading that the power steering shaft will fit in the 1964 column. The only column difference I know is whether it has a shifter in the column (for manual transmission in 1964). Perhaps manual column housings were longer, but would only be for cosmetics. Many people cut their manual shaft and drill a hole for the coupler. When going the other way, to a manual box, they add an aftermarket length adapter. You might swap your manual shaft with a power shaft with another hobbyists since more people go to manual steering to clear headers.
While "in there", assure your column has a seal at the end to keep engine bay fumes and noise out of the cabin. OE was a rubber piece, which is repro'ed. One member here posted a fix using a ball-bearing.