I had a 2nd generation Fila "Astroceramic" Champion that I used around 1988.
The original Fila Champion (early 80s) was IMO one of the coolest rackets of all time.
Anyways, the Astroceramic line of frames seemed to be named after the space shuttles - Columbia, Challenger, Discovery - something like that if memory serves correctly.
Coming from the late 80s, they are old school by today's standards - heavier and more flexible.
A new one is a great find.
I would think pretty much any string will work well in it.
Head Classic Midplus & Dunlop MW200G