An interesting thread for sure
From my Ka days the 1.6 and 1.7 Sigma conversions were quite well documented with the 1.6 especially being known for fitting as if it were meant to be there
. If I am honest it does make you wonder why Ford never used either engine in the great chassis of the Ka and seemed to used the leftovers from Brazil and Bridgend (I.e the RoCam and HCS/Crossflow (sorry, Duratec)) engine.
All being said, I do love the idea of a Zetec or a CVH under the bonnet. From the old days however, not many CVH turbo conversions worked in the long term ; heat was the biggest issue (overheating) in part due to the radiator not being able to fit with a T3 turbo in place. People tried to work around such issues (fitting a second radiator etc.) but you would always see the cars for sale and then come back to the owner in a strange twist of fate. A few were reliable with larger radiators but the owners seemed to compromise on the turbo size, thus seemed like 'losers' in the dick length competitions.
With that in mind (unless there has been proven to be a CVH Turbo has been reliable with regular driving and years of use) I would personally look into the Sigma engines and Zetec. Duratec is a great shout if the engine is not too tall
Now it's image time
[imag]http://www.google.co.uk/url?sa=i&source=images&cd=&cad=rja&uact=8&ved=0CAg QjRw&url=http%3A%2F%2Fpassionford.com%2Fforum%2Fpi ctures-video-and-photoshop-forum%2F279523-show-us-your-ka-s-turbos-ect.html&ei=KjufVK6NDY_B7AbRpIGgDg&psig=AFQjCNG0g4 AR0RgIJ7UY3em0ZcqRjOBY-w&ust=1419807914292196[/img]
And a CVH