I've done it.
I'd recommend you use a little trial and error.
Using the standard struts inserts, move the cup up by one inch higher than the point the cup would sit if you didn't load the unit at all. This pre-loads the spring, and stops them falling out under full 'droop'.
Use only 2 'good' tacks with the mig, and trial fit it, preferably with the guards on and engine in. If it's too high, move the spring cup down the strut the amount required. The travel in shock absorber should be used to it's maximum. And the spring should be as loaded as it would be in the 1200 struts.
Remember, you can get the springs made to suit the required height.
I don't think I can tell you exactly, as my brother has my 200B/1200 struts. On his 1600 using the 1200 springs.
You can try and guess the position from my online picture..
http://www.geocities.com/motorcity/2330/diff_str.jpgGood luck, if I get better measurements, I'll let you know.
Chris