Argh! This damn fan shroud/alternator problem is driving me nuts. I found a local alternator specialist only to receive the usual British quality of service: the square root of bugger all. So back to square one - almost.
I finally found the same shroud as I have on my car - from hunting through hundreds of images on Google I've spotted this from Paruzzi, a site unknown to me until now. (and thanks to Brexit, not one I can easily buy from because most European companies have temporarily stopped trading with UK buyers because of the paperwork involved.)
They also do a different oil filler modification, which I wish I had..
Going back to the fan housing, the biggest issue I can't get my head around is the lack of bolt holes on the fan frame - it should have 6 bolt holes like this, through which the alternator is bolted and the vane is then attached to:
And I find on the pelicanparts forum a useful pic that shows the bolts holes in the fan housing. This now makes me think that whole 'ridge' that holds the 6 alternator mounting holes has been machined off:
Or mine is something completely different, because there are no machining marks around that top edge.. It's still got a rough cast edge to it.
Ah well, I'll keep looking. At least my aluminium sheet and rubber edging arrived today so I can make a start on fabricating new tinware. :-)