Most yarn is put up in 50gm/1.75 oz balls, so you’d need 3 of them, but different weights have different yards or meters in them. 8 ply is equivalent to fingering weight. So look at that weight yarn and probably 3 50gm balls would be enough.
Here’s an article that explains the ply yarn weight system and its conversion to US weight. And I lied… it’s really DK weight. I get confused on the conversions sometimes…