CRC, the following is a photo of a Hydro head.
Note that there is no
lock nut and broken off adjuster above the push rods. On this one the recall HAS NOT
If the one you are looking at is like the one above, frankly, considering the trouble and probably expense you are going to have to go to I would be inclined to leave it alone.
Having said that I'm of the impression that a hydro engine that was sorted before
it clapped out is a fine tractable beast. Quiet too. I certainly liked mine until it clapped out. (Failed because the recall had not been done). They do have a lot to recommend them.
You need also to be pedantic about putting in the correct grade of oil with them though. 5w40 full synthetic. (though I used 5w60 in mine.)
If you do a search on this site for "Hydro Recall" you will find a lot of info about all this in previous threads. Like this one;http://wildguzzi.com/forum/index.php?topic=71068.msg1104503#msg1104503