Looks as if Elspeth may also have been known as Elizabeth. This is not uncommon because the name Elspeth is a variant of the name Elizabeth.
William McIntosh, son of James McIntosh and Elisabeth Syme, was baptised in Abernyte in 1847. There's also a baptism of Charles, son of James McIntosh and Elizabeth Sime, in Abernyte in 1852.
The 1861 census, Longforgan, lists James McIntosh, 44, wife Elspeth, 40, and Agnes, 21; Innes, 13; Charles, 9, David, 7; Allan, 4 and an unnamed baby. William McIntosh, 14, born Abernyte, is a servant in the household of James Playfair, also in Abernyte.
Allen Aird McIntosh was born on 12 January 1857 in Longforgan, and Janet Sim McIntosh on 12 August 1861 in Errol, both to James McIntosh and Elspeth Sim or Sime.
In 1851 they're in Abernyte. James is 35, wife is Elizabeth, 31, and the children are Agnes, 11; John, 6; William, 3; and Innes, 1.
James McIntosh and Elizabeth/Elspeth Sim/Syme were married in 1841. The banns were called in both Coupar Angus and Kirriemuir, which normally means that one of them resided in Kirriemuir and the other in Coupar Angus. Janet Sim McIntosh's birth certificate will confirm the date and place of her parents' marriage.
Elspeth McIntosh or Sim, mother's maiden surname James, died in Longforgan in 1878 aged 55. Her death certificate will tell you whether or not she was a widow, which will help to narrow the search for James' death.
Elisabeth Sim, daughter of John Sime and Agnes James, was baptised in Inchture in 1817.
You can view the originals of all this information at
www.scotlandspeople.gov.uk. Happy hunting!