UK government papers from 30 years ago, released by the National Archive, include briefings from David Willetts.
He said Scotland benefited from Â£900m "over-provision" compared with England.
At the time he was serving in the Number 10 Policy Unit.  He later served as a minister under David Cameron and is now a Conservative peer.
In a briefing he wrote for the prime minister, dated 8 January 1986, he said Scotland was a "juicy target" for the Treasury to "pursue".
But he also noted that George Younger - who was Secretary of State for Scotland at the time - was "reported to be very 'emotional' on the subject" of cuts and "may well threaten to resign" at the prospect.
In another document, from the 12 February 1986, he said the position of the Tories in Scotland was "so bad that it might not deteriorate any further", and that the "envious North of England" might "welcome an attack on the pampered Scots", leading to more votes for the Tories.
Commenting on the release of the files, SNP MP Stewart Hosie said: "No one will be surprised at secret Tory plots to slash Scotland's budget."
He added: "To describe Scotland as 'pampered' and  a 'juicy target' may go some way to explaining why the Tories were wiped out in Scotland."
An advisor to Margaret Thatcher argued that the "pampered Scots" were a "juicy target" for spending cuts, according to newly-released records.