Andrew,

You hit on most of it, and will no doubt stumble onto things it is hard to foresee. Get the transmission first, get it mounted up and set into the car with a jack under the transmission extension housing where it would be. You can order C4 Falcon mounts at Falconparts.com.

Go to a driveline shop (Drivelines NW if here in the area) and get the transmission yoke for that transmission. Let them know the original shaft tube diameter. Then you can insert it into the transmission with about 3/4" left to insert (for forward movement as the rear-end travels upward pushing on the shaft as it does) and measure center of yoke to center of yoke front to rear for the correct length. This will get the drivetrain set into place.

At this point the rest should be pretty much the same. You should be able to use the factory throttle linkage, but the kick-down linkage may have to be fabbed as a cross between Lokar/McGyver.

Exhaust will be custom, mostly, but the downtube from the head is pretty common on any car with this motor.

Radiator may be the same, but you'll need to verify whether the outlets are all going the same as the 170. I'm not sure whether they ever used reverse rotation water pumps, but I'm pretty sure you can put all the 170 front bits onto a 200 to keep all those bits the same.

Ignition parts may be newer, but I'd be upgrading those anyway, if I were you. Pretty simple to do and makes for a far more reliable driver.

The shifter linkage on the column will be wrong, but call Falconparts.com and I'm pretty sure they can get you the parts to change these. If not, you'll still be able to hook things up and get things from park to drive - if for now by feel.

Good luck!