That helps, thank you.
I am working on the theory that his grandfather, also John Trueblood, dies in Spring 1683 and leaves him a legacy. This makes sense as John's two sons are dead (one imprisoned for being a Quaker and dying in gaol, one in the Great Plague of London). The old man, a prosperous blacksmith, would have had only two grandsons living near him in Lincolnshire, both fellow Quakers. That might have supplied the funds for passage, funds to get started and a slave or two. Sadly the older John's will has not survived.