QA1 style stock replacement k member

The problem I encountered with the QA1 member is that they do not offer it beyond a 1972. I don’t believe it will work for my 73 Dart? Unless I’m wrong, the spool mount is what I need to install a V-8 in place of my slant six?
This is my first build with my son so I may be wrong but I am looking for one for a 73 A body to hook a 340 to a 727. Would this work? I hope to go aftermarket control arms with front disk brakes as well.

Wait.....I just had a brain fart!!!!!!!!?????????

If i am building the car from the ground up and swapping a S6 to V8 why does it matter what type of K member I use as long as the mounting points are for a V-8. Can I not just get the correct motor mounts to match the member when I build the 340 as long as the mounting points for the member are all the same? Now I’m really confused?? Can someone please shed some light on this for me???
Dan