The problem with wound .020s is that they have a very thin core, and therefore prone to breakage. I had one break on me at E, not even reaching F.
Looking at Rotosound's 8 string set, the .020 is tuned to G. I doubt this is a wound string, I don't think a wound would take the tension. If it's a plain steel .020 you could just use a guitar string instead. Rotosound guitar strings are long enough to use, just detach a bass ball-end from a dead bass string and thread it onto the guitar string, slide it up against the guitar ball-end... instant bass string
