Ullar,

It was a combination of factors. The original track did not appear to be through bolted. I suspect there is a strip of steel that was basically embedded, and then holes drilled and tapped to accept the screws for the original Goiot track. There was no sign of any problem with the track. After consulting with a few riggers who had seen similar installations, we decided to mount the new track on top of the existing.

Here is a link to a photo of the track right after it was installed. We used Lanocote on the machine screws to prevent dissimilar metal corrosion. That's the orange colored goop you see in the photo around the screws.
https://dl.dropbox.com/u/105731786/amel_track.JPG

The beauty of this approach is we were able to use off the shelf Harken hardware that is both robust and readily available.