Read page 3 of
http://www.talkmorgan.com/ubbthreads.php/topics/131105/3 You can ask the dealers too who have driven the test car or Kevin Vernon at Tudor Vernon who has done two conversions.
Tim Harris who is on TalkMorgan is haveing his car done today Friday, so ask him too.
https://sites.google.com/site/morganatica/suspension/springs-progressive-rising-rate for dealers who fit.
Regards PJB.