tons of 3 to 4 speed swap qustions, and/or putting a 360 behind my 3 speed???????????

hey guys. i got a 70 duster with a slant six, and 3 on the floor.
i want to put a 360 out of the junkyard in it after a rebuild, but have no clue what to do........
will the 3 speed last under the 360 torque?
can i use the /6 bell-housing that is in the car?
what starter do i use? what flywheel and clutch plate?
is it a waste of time trying to keep the 3 speed?
i do not really care to go to a 4 speed at this time, but that slow azzz /6 has to go.lol no offence.

if someone could give me some pointers, i would really appreciate it very much