I do not have any personal experience on this matter, but did see this post.
http://forums.audiworld.com/showthread.php?p=18190491
It seems to imply that it is not possible. There is a little data to glean in the post
#1
I have a ten valve turbo and i got a friend selling his wrecked 20 valve to me ( turbo too) his block is cracked but heads are ok. will it fit without too much trouble on my ten valve engine?
#2
I do not have any personal experience on this matter, but did see this post.
http://forums.audiworld.com/showthread.php?p=18190491
It seems to imply that it is not possible. There is a little data to glean in the post