There are 2 types of units in late 140s and 240s - the UCOMBU (not equipped for aircon) and MCOMBU (which is). All OZ-market cars got MCOMBU because Australian summer, so that's all I'll talk about below.:
They used the same basic system from YM1973 - but the 73 is a 1-year only special, with a vacuum-controlled heater tap, a 1-year-only heater core, different vacuum shutter bellows to later models, and 2 aircon evaporator drain holes.
140 YM 1974 to 240 YM 1990 used basically the same unit, made from white bakelite. 1990 moved to gray plastic for the main body. Aircon for YM91 on had a larger parallel flow evaporator fitted, and the system switched to CCOT instead of a TXV. The heater cores from 74-93 are all the same.
The heater fan motor changed from a multi-winding Elecrtolux unit to a cheaper permanent magnet motor in YM 1978-79. The cheaper permanent magnet unit uses a resistor pack and a different rotary switch to the earlier multi-winding unit, which doesn't use any resistor pack to vary fan speeds; it switches windings. The official 240 aircon Green Book (can't remember the TP number right now, but will find it if you insist) shows the complete modification process to switch from the multi-winding motor to the later type, which was all Mother Volvo stocked as complete replacement motors.
Most people don't like the multi-winding units, which sometimes wear out their brass bearings, but most of them fail due to worn brushes, which are still available as spare parts. (See [36] in the OP's pic). The permanent magnet motors aren't repairable and must be replaced as a complete unit.
Contrary to popular opinion, I prefer the old multi-winding motors, and have changed plenty of worn brushes in my day. One or two of them have had to be junked because the brass bearings were shot, but I'm not a fan of resistor packs. Also, getting a good brand new permanent magnet motor these days can be a bit hit and miss, too - there are reports of new-in-box VDO motors being wired back to front, and of having abnormally short lives.
With all that said - the 77 264's HVAC box will be the same or very similar to your 83 240 model HVAC. However the 83 may have had the permanent magnet motor with resistor pack fitted at the factory; the 264 is more likely to have the multi-winding motor. If you're going to fit the 77 264 box as a complete unit to your 83, make sure you also get the fan switch from the 264.
Edit: parallel flow, not plate and fin
