Placing RC4 cipher to top of the list fixes the FTP-SSL file upload problem (“550 The supplied message is incomplete” response to uploads) with IIS7 & 7.5.
(same as one of the fixes in : Move “TLS_RSA_WITH_RC4_128_SHA” to the top of the priority list.)
Unfortunately the given method for doing this (Group Policy) is non workable due to the 1023 char limit in the group policy value field.

Use IIS Crypto to make the job easy peasy. Now FTP-SSL uploads work.

Settings as below: