Hi Richard,
This has been puzzling me too, but wrt my spitfire. The concensus seems to be, only use a single rubber spacer, and if you have to adjust the body, use
more or less aluminium ones. All very vague I'm afraid.
The most definative I've managed to find came via James Paddock which is a page from the Moss Europe catalogue, and is to be viewed as a starting
point.
The positive approach, apparantly, is to remind yourself that the tub is in one piece, not like the Herald or Vitesse!!
If you squint you'll see the mounts marked out.
http://www.moss-europe.co.uk/Shop/ViewProducts.asp...