Just found this while trawling around..
For Trigger Maru Overhauled: It should be noted that SCAF is incorporated in the latest TMO 1.7 edition released March 31, 2009.
In this thread; http://www.subsim.com/radioroom/show...126016&page=13
The only mention of SCAF (which I had never heard of until now) in the TM documentation was a mention in the credits. I suppose the moral of the story is, don't install mods until you have read and understood all changes implemented.
So I think that the only thing I was doing incorrectly was inputting target range on the stadimeter using the wrong top reference point. I haven't tested it yet and hope I'm correct - only time will tell!
Thank you for your advice Lord Kelvin, the speedy reply is much appreciated. 