An FAA 8130-3 is acceptable for a second-hand or repaired part as long as it's issued by a repair station that has EASA foreign repair station authorisation
Very true; I forgot to mention this.
That is how the ridiculous engine overhaul situation (of some years ago) was solved, when the only place where some engines could be overhauled was in the USA, but the company there did not have EASA approval. The overhauled engine was technically secondhand
However I am not sure if any of the U.S. specialist autopilot repair shops are EASA approved and can thus do a dual release 8130-3.
Can't Lees Avionics do STEC work?