Yeah, I like the look of those 240 arms but I'm a little confused... You said if you weren't getting adjustable arms you'd get these: But those arms ARE adjustable. I'm not sure what you meant...
I don't know if the same rods work for the 240 and the 300, but I did notice that the same seller has different rods for the 300 listed and they have the same solid mount bearings as all the others. link to ebay auction for 300ZX arms