1974 Duster 340 w/ 727 to A833

What is a OG 727?
The OD 4spd trans has a large front retainer which could be a problem in finding a bell housing to fit even if you grind down the retainers outside diameter smaller.
And now the question is do you want an overdrive trans? Do your calculations on rpm and speed!

IIRC, the 727 shares the driveshaft with the 4spd trans. Same yoke, same length. Make sure the U-joint is the same size for install ease.
No new cross member needed.

Find an exploded veiw of a Duster and anmanual trans.