Wow I've never heard of the David Library of the American Revolution. Thanks I'll be contacting them ASAP!
Here's a reply I received from the National Archives...
Thank you for your recent inquiry concerning John Morton, which has
been referred to ALIC: Archives Library Information Center. Morton did
not leave much in the way of personal papers, at least as far as I can
locate. The entry for him in the Dictionary of American Biography only
provides the following information for sources:
"[Sources include: Minutes of the Provincial Council of Pa., vols. IX
and X (1852); Pa. Archives, 2 ser. IX (1880); M. A. Leach, "John
Morton," Am. Scandinavian Rev., July-Aug. 1915; J. H. Martin, Chester (and Its
Vicinity), Delaware County, in Pa. (1877); Geo. Smith, Hist. of
Delaware County, Pa. (1862); H. D. Paxson, Sketch and Map of a Trip from
Phila. to Tinicum Island, Delaware County, Pa. (1926). There are brief
biographies of Morton in the various works on the Signers, though they are
for the most part mere eulogies of character. Since there were several
contemporaries by the same name, no portrait of Morton, the Signer, is
considered authentic. His tombstone in St. Paul's churchyard at Chester,
Pa. and the tablet to his memory in the Independence Chamber of the
State House in Philadelphia give 1724 as the year of birth, but it may
have taken place early in 1725, N.S.]"
The Journals of the Continental Congress are available in full-text,
and searchable, on the Library of Congress' Century of Lawmaking web site
at http://memory.loc.gov/ammem/amlaw/lwjc.html . A search on the name
Morton does retrieve a number of citations that may be of use to you.
I hope that this information is of use to you. Once again, thank you
for
your interest in the National Archives and Records Administration.
Sincerely,
National Archives and Records Administration