Turns out the pulley wasn't right after all. :banghead:
It's too deep, doesn't align with the water pump and alternator. And I think the diameter is too small. The one Ulf sent is 145 mm OD and the groove center is roughly 50 mm from the base.
I seem to remember that the pulley I need should be roughly 35 mm from the base to groove center.
The other one I have is too large, if I align the grooves, the pulleys will touch. Bollocks. Back to square one ...