K Member Question/ID

Dad bought a 73 Duster a few weeks back for us to work on. Didn't come with a trans or motor.
Originally was a 340 car with discs, but this one has drums, guess somebody switched it out with this one.

Is this a 68-72 A body I6 k member?
My Dad and I are planning on putting a 340 or 360 in the Duster.
Would we be able to just use those conversion mounts for a sb v8 or would it be best to just find a v8 k member?
Thanks for the input.