Could she be the Elizabeth Pengelly buried at Talland, 21 Oct 1863, age 84, abode West Looe?

Info from Cornwall OPC.
(presuming that the Elizabeth buried at St Martin by Looe, 5 April 1861, just before that census, age 83, abode East Looe, was the the lady living in East Looe in 1851)
There is a memorial inscription, Talland parish church, John Pengelly, died 28 May 1855, age 73. But no mention in the index of Elizabeth.
Re possible other children, it's difficult with there being quite a few Pengelly families in the area, but have you looked into this marriage at Maker, 30 June 1828
John Willcocks of the "Windsor Castle" and Ann Pengelly, a sojourner in the parish
BT here (marriage is not on Cornwall OPC)
https://www.familysearch.org/ark:/61903/3:1:3QS7-L93K-G6Z6?i=84&cat=1833620In 1841 John and Ann Willcocks are in Back Street, West Looe, next household to John and Elizabeth.
In 1851 they might be all together there? Ann, 40, born West Looe.