It is my impression that Strada e Corsa is not a serious or reliable business, as they have failed to make any response to two e-mail inquiries I've made during the last two weeks (other than one automated 'out of the office' reply, which confirms that my message was received). Even if the parts I seek are not available (although some are shown on their website), it is unprofessional to simply not respond, especially after utilizing this forum as a free advertising medium.
Notwithstanding the frustration evident in my prior message, I would like to report that Strada e Corsa has supplied a very good example of the relatively rare Marelli regulator that I needed, and that Mr. Schouwenburg has performed with great efficiency and courtesy now that we have made contact. I will not hesitate to do business with them again.
Many thanks to Philip Leemans for bringing them to my attention.