The purpose of this blog is to list new, interesting and unusual Bibles.
You say that he wants a "line-by-line interlinear" as opposed to a "verse-by-verse interlinear." I think of verses as essentially being lines.Did you mean to say "word-by-word interlinear"?There are a large number of both online and printed verse-by-verse parallel Latin-English Bibles. If he is looking for a word-by-word interlinear functionality, he'd probably be best off with the online Perseus version.
Yes, word-by-word is probably a better description. I believe he is looking for a printed edition as well.
There is the douay rheims clementine vulgate interlinear bible available in hardback leather for £60 from www.cenacle.co.uk.