OK. It seems I stand corrected. 
Doing some more research, it looks like Opel also only sold the 3.2 with an auto box, like Vauxhall did. Pity.
Since the 3.0 is quite common with a manual and I also saw one 3.2 manual for sale, I thought the 3.2 also came in manual. But it looks like the one 3.2 manual I saw online for sale was probably a conversion.
But the 3.0 manual is indeed way more available than back in the UK. I think the reason is in continental Europe most people like manual cars.
Now the question is, is the 3.2 better than the 3.0? Because it only makes 7hp more. But the 3.0 is easier to tune up it seems.
So is the 3.2 better, and that much better than the 3.0 to warrant buying one and doing a manual conversion rather than just buying a manual 3.0?
There's a chap on here with a good deal of knowledge of this question - which is the 'best engine' the answer is - several.
MarksDTM suggestion is the 'ultimate' Vauxhall/Opel V6 is
"So.....from the stock GM parts bin.
3.2 inlet with injectors or fit 3.0 and the FPR from a 2.6/3.2 (slight increased rail pressure, worth having as it costs nothing)
3.2/3.0 inlet divider plate
2.5/2.6 heads which must be ported to match the inlet divider (2.5/2.6 heads have smaller ports than the 3.0/3.2) and 3.0/3.2 exhaust valves (sodium filled)
3.0 cams
3.2 bottom end
2.6/3.2 exhaust manifolds
2.5/3.0 front pipes and cats
3.0 electronics including DIS pack ecu etc with EGR blanked/removed and SAI removed
This gives the better injection setup (3.0), largest cc (3.2 which includes forged crank) with compression ratio restored (2.5/2.6 heads have a smaller combustion chamber), best flowing inlet and exhaust setup."
If you're really after making the best of the best, this is the way. As for just buying either a 3.0 or a 3.2, then it's apples and oranges, horses for courses. (sorry if they're meaningless English phrases, what I mean is there's advocates and reasons to own either)
