I did the conversion on my 68 roadrunner, plated off the shifter hole, removed the z bar, had to add cooling lines / B&M cooler, neutral safety switch wire/ relay, throttle pressure linkage or (kickdown linkage)must be added. It is very important and must be working correctly if not it will damage the tranny .or go manual valve body and no kickdown linkage is necessary. drive shaft was the same.
Automatics are less forgiving then four speeds when it comes to alignment you"ll probable be fine.
If your not going to go through this process of checking the crankshaft centerline to the 727 make sure there's no binding when the bell housing is on the dowels and the converter mates up with the crankshaft, it should be able to spin the converter with one finger. (bell housing bolts secure)
As per the Mopar bible,Mopar Chassis(Speed Secrets & Modifications for Chrysler RWD Racing Cars) to align a 727 relative to the crankshaft centerline . you would have to have the empty 727 case to check.attach a dial indicator to the crankshaft flange and check the run out on the front pump outside diameter surface in the case..008" is the maximum runout allowed.They sell off set dowels to bring it with in the correct tolerance's if needed.
Torque Converter selection. How much stall? selection is based on many factors, car weight, engine spec's, final drive ratio..street / strip driving / a qualified transmission shop can help you with that selection. picking the correct converter is important to get this right thee first time. your wallet will thank you.
Other things, starters/flywheel (10 tooth starter/ 130 or 143 tooth ring gear on the converter). also if your engine is externally balanced you will need a flex plate to match and the converter needs to be balanced., exhaust system headers/ manifolds ? possible modifications
final thoughts, Shifter of your chose .I like the turbo action cheeteh. build the tranny for the engines power output and how your going to drive it. If your going to put a shift kit in replace the rear band servo piston and retainer ring they are prone to failure due to the heavier spring that is installed with most shift kits (Mancini racing sells them)ask me how I know :-(. bolt in sprag, deep pan.... I did the conversion to make my car more consistent at the track. hope this helps