Sorry Maple but that's not quite correct.
The Diana G80 was sold in .177" as a normal sporter alongside the .22" guns, I know this is true as I bought a tuned .177" G80 by mail order from Airgunaid on behalf of my brother as he was under 17.
Unfortunately, after hanging on to my brother's Airgunaid tuned .177" G 80 for years he asked for it back about the same time as I joined the forum, so I never have had the chance to open it up and see how it was tuned.
As far as I can remember there was a target version of the G80 as you say, and Airgunaid sold a target version of the G80 in .20" alongside their .20" sporter.
Again from memory I think these were badged as the Airgunaid TR and Airgunaid SP --- a search on here will throw up some results on this to correct me.
All the best Mick