73-76 a-body k-member

So, lemme see if I got this right:
You want to install a BB into your 73 Duster, that currently has a /6 K-member; is that right?
How about you put your location; town or nearby town, and state, into your side-bar, so we can see where you are at.

Do you have a BB transmission?
A BB rearend?
BB brakes?
BB suspension?

I can help you with all of that, oh wait no autotrans, but if you are in Florida, shipping might hurt.