Newbie With Engine(s) Questions...

Welcome !!
Big blocks in a- bodies make fun cruisers !!
They have the torque to boil the hydes at will !!
The low deck 383-400 make it a bit easier but rb still do work .
One thing you might try is finding a straight 73 they seem more plentiful, and cheaper, plus they still have the tail lights in the bumper . Then get a scamp 70-73
Bumper or 70 dart bumper nose and doors with wing windows and you basically have a 70 dart !!
This can be done pretty cheap if done right !!
It don't matter if it's a 6 car , just get Schumacher mounts .
As far as stick or auto it can be converted easily !
Good luck
Jim