Question: That reminds me. I have to swap a SMC on a 2010 A1286. I don’t have an exact donor. Can I use a donor with a different processor?
Answer: [Piernov] as long as it's the same model donor board it's fine.
In some cases you can use one from similar boards. SMC firmware is exactly the same on 3476 and 3536 for example, I guess it's the same for 00163 and 00426.
In some other cases SMC from similar board should work fine but there may be some discrepencies (between 11" and 13" Air)
In some cases it'll not be 100% compatible but enough to boot, then you can force flash the SMC update for the correct board… may work.
For a 2010 A1286, the 2010 A1297 may be close enough for example, dunno.