I've been thinking of retro fitting a Ph2 (2001) climate control into my 97 Ph1 (both Spiders), but not even started the investigation. But I would be interested in seeing the list of Ph1 parts you have put together - it might help me decide if any of the Ph2 parts can be used if its not feasible to fit the whole climate control system - can you post the list?
I have a spreadsheet somewhere. I'll dig it out.
Climate control adds a lot more work. You'll need to swap the entire heater unit to ph2 owing to the electric actuators. You'll need a temperature sensor in the door mirror ( or somewhere else maybe ). The one area that may prove very difficult is whether the phase 1 ecu can be interfaced.
I've had a look at this myself now. In summary, it's not easy! It's probably easier if you start with a non aircon phase 1!
This following is based on looking at the wiring of an early Phase 2 Twinspark with M1.5.5 ECU and looking at part numbers etc.
Interfacing to the car's ECU is probably not a problem if your car has the M2.10.4 ECU. M2.10.3 is probably not possible ( as those cars didn't have the four level pressure switch in the high pressure circuit ).
The aircon wiring ( I'm seperating aircon and climate control here ) is not too dissimilar to the phase 1. You'd actually end up removing some stuff like the second compressor engagement relay and the simple pressure switch in the high pressure circuit ( more on that later ) as the climate control ECU takes some of the effort.
The majority of the additional components for the climate control part are in or around the phase 2 heater unit so the phase 2 heater/climate loom could probably be reused ( depending on how it integrates with the car ). For the external temperature sensor ( if keeping it in the mirror ) you'd need to add some pins to the multi-way connectors between the passenger door and A pillar.
You'd need to rewire the heated rear window switch to the climate control ECU.
Now the not so good news.
When selecting rapid defrost on a ph2, it switches on the heated rear window. This works by the climate control ECU telling the Integrated Services Unit ( N82 ) to switch on the HRW. Unfortunately, N82 is different on ph1 & ph2 and the ability to receive this signal by N82 is not possible ( at least the wiring isn't there ). N82 is also responsible for switching on the rapid defrost LED and this won't happen either. This isn't a huge problem, it should be possible to work around or even just switch the HRW on manually. It may even be possible to substitute the ph2 N82 instead and add the necessary wiring but I've not looked into that yet. You may also be able to retro fit auto drop windows if you update N82 - but this is purely speculation at the moment.
And now the really bad news!
The Phase 2 aircon system is totally different to the phase 1. Starting at the bulkhead, the seal to go around the heater and aircon pipes is different. The pipes around the engine bay are different. The drier/filter is different. The condenser is different. The compressor is different. In part this is because the system uses an evaporator valve at the heater unit which the phase 1 does not ( I think that's why the phase one has a pressure switch in the low pressure circuit and why the phase 2 doesn't need it ). If the ph1 piping can be modified or persuaded to fit on the ph2 evaporator, you may
be able to get away with a hybrid system. This would allow the use of most of the ph1 aircon stuff in the engine bay. It's also dependant upon that ph2 evaporator valve and the ph1 low pressure circuit pressure switch. I can't advise on that at the moment as I don't know enough yet.
If you're willing to pretty much strip out everything from the phase 1 aircon system & your car has an M2.10.4 ECU it is probably possible to fit climate control to a phase 1. I don't know if it can be kludged in with the phase 1 dashboard but it would probably be simpler to fit a phase 2 dash and modify the wiring for the switches ( fogs, headlamp aim, fuel cap, instrument dimmer etc ). The actual bulkhead & crossmember have the same part numbers between ph1 and ph2 so there shouldn't be any body modifications necessary. The steering column support bracket has a different part number but that may be for other reasons besides the heater unit. Some of the bracketry behind the bumper for the drier filter has changed but they're just bolt-in anyway. I don't know if the ph2 condenser will mount to the ph1 radiator at present.
I shall continue looking into this as I'm now considering going straight to retro fitting climate control in my car instead of going just to aircon but I'm somewhat ambivalent about fitting a phase 2 dashboard in a phase 1.