Thanks, guys.
I re-hung the drivers door today with some better spacers to make sure I was happy with its postion before proceeding.
After that, I spent the afternoon finalising the rear tub postion and installing the Marlin supplied new striker plate.
Took quite some time to get in right postion but the sound of the catch closing is terrific.
Lots of detail included in my pictures as it is not covereed in my 'build manual'
http://www.flickr.com/photos/peters-bmwmarlin/
Now I just have to do the passenger side.......