Flaming River Power to Manual Adaptor

I bolted in a manual steering box last night in the 69. When I was tapping the shaft down, my vise grips slipped, and I hit the joint, causing it to fly into a few pieces. I also found out that the splines are bigger on the manual box. So, I gotta buy a new joint.
My question, should I get the Flaming River (FR-1505M) power to manual adaptor? It's about $190, but it says its for the conversion. Or should I just buy a swivel joint for a manual and extend the steering shaft? I want it to pin to the steering shaft like the factory unit.

Can you post a picture? I used the part from Mancini and the splines matched perfectly between the column and the adapter and the adapter and the box.

It might be too late but did you notice that the splines are keyed?