Truck 727 for my Dart.

If it's a light truck it'll fit but if your Dart has a floor shifter the trans may not have the needed lower shifter linkage mounting tabs.

A 268XE cam in a low compression 360 isn't the best match and may not have a bunch of low end torque. For that reason I would only use a converter built for it. Any off the shelf converter is a shot in the dark IMO.

BTW: I see you stated you already have the 727 but you might want to consider selling or swapping it for a 904. It'll be faster, more fuel efficient, and plenty reliable for what your doing. JMHO