I have recently formatted an English language edition of the Isaiah Targum for BibleWorks: The Chaldee Paraphrase on the Prophet Isaiah Translated by Rev. C. W. H. Pauli.
The following English Language translation of the Isaiah Targum of Jonathan was compiled by Rev. C. W. H. Pauli for the London Society for Promoting Christianity among the Jews in 1871. Notably, this work, at times, displays a Christian tone. However, while the text can be compared with the TAR/ Comprehensive Aramaic Lexicon database within BibleWorks, Pauliís edition is helpful for those who desire to study the Isaiah Targum.
Pauliís footnotes, which at times are helpful, are available for viewing within the BW Analysis Window.
This edition of the Isaiah Targum of Jonathan is found at various websites and is public domain.
Michael Hanel, like always, has been kind enough to host the file for download here:http://bibleworks.oldinthenew.org/