Quick Google search shows the receiver was produced 1967-69, the speakers (a version) 1975/6, so no, they weren't meant to be sold as parts of a system as such.
That said, there was an earlier sp-3000 (no a) but those were from 1970 so again doubtful they were part of a "system" as such. Of course either will work with your receiver, but as far as being "made for your receiver" I don't think so.
Don't know a lot about Sansui but Infinity reused model names/numbers many times, to the point it can be confusing. For example, "which XXXX do you mean, the old XXXX or the newer XXXX".