Painlessly? Nope, but it depends on your tolerance for pain.
Is the Charger transmission a 904 or a 727? 904 will fit, 727 may need some tunnel massaging at the pinchweld, as already stated. '65 trans is cable/pushbutton shift, '77 is mechanical linkage, either column or floor shift- you'll have to come up with your own shift mechanism. The '65 has a ball and trunion output shaft, the '77 has U joint and a slip yoke. New driveshaft time, might be able to use the Charger shaft if you have it shortened. The speedometer drive is also different between the two. I'm pretty sure the Charger's kickdown linkage won't clear the firewall of an early A body, either.
Engine will fit easily enough, slightly modded 273 mount brackets from an early A will do the trick. You need to find the early V8 cable throttle linkage, your slant 6 linkage is a pivot rod system. You'll need a V8 centerlink to clear the steering.
Exhaust will depend on if you have power steering or not. Some manifolds and headers clear, some will not. The only thing that's a guaranteed fit is the early A 273 driver's side manifold, but you also need to be aware of exhaust manifold interference issues with later heads like those '77s.
Then there's radiator, rear end, brake and suspension upgrades that become necessary as others have already said, and most of that won't fit from the Charger.
Really, there's like a kazillion threads on this already, you need to fire up the search button, grab a six pack and settle in for a long night's worth of reading.
