I found the same information about your grandfather aboard SS AMASA DELANO (note correct spelling) on the voyage from Wales in October 1944 but no additional information about any other ship in which he may have served. I found the information via a search of Ancestry.com, which may be your source as well.
Your information that the Navy transferred him to the Armed Guard Center in Treasure Island (i.e., San Francisco) may be significant. Presumably this occurred after his voyage aboard AMASA DELANO. My experience with Ancestry.com is that records for ship arrivals on the West Coast are much less comprehensive than for arrivals in New York City, which was the destination of AMASA DELANO in October 1944. Worse yet, when Ancestry.com lists a ship arrival on the West Coast during World War II the record often does not include a list of Armed Guard personnel aboard the ship (instead listing only the merchant marine crew and any passengers), even though Armed Guard crews were almost surely aboard. (In fairness to Ancestry.com this is likely a function of the recordkeeping of the time rather than a shortcoming of Ancestry.com.) So while your grandfather probably was assigned to one or more ships that departed and/or arrived in San Francisco or other West Coast ports in late 1944 and 1945, it is not a surprise to me that Ancestry.com does not list him.
From the other information you provide I presume you may have your grandfather's entire military service record, either because he kept it himself or you or your family requested a copy in the past. If you suspect you do not have his complete record (which would generally list the ships to which a sailor was assigned), see http://armed-guard.com/searchmil.html, section II.A.1, Records of Individuals - U.S. Military, for instructions about obtaining a person's military service record.
As to information about AMASA DELANO, she was constructed in 97 days by the Delta Shipbuilding Company in New Orleans between March and July 1944. She survived the war (including a later voyage to northern Russia, the infamous Murmansk Run) and was laid up in the Reserve Fleet ("mothballed") in the Hudson River in 1948. In 1951 she was sold to a private shipping company, sailed under the Greek and Liberian flags under three different names, was rebuilt and lengthened in 1956, and was scrapped in 1968 in Taiwan. See http://shipbuildinghistory.com/history/shipyards/4emergencylarge/wwtwo/delta.htm and scroll to hull number 116, and http://www.mariners-l.co.uk/LibshipsA.html and scroll to the name of the ship. The ship was named after Amasa Delano (1763-1823), a Massachusetts sea captain who made three voyages around the world and wrote a book on his adventures.
As to the voyage in which your grandfather sailed in AMASA DELANO, the ship departed New Orleans about July 10, 1944. As such it was both the ship's maiden voyage and probably your grandfather's first voyage. AMASA DELANO proceeded to New York where she loaded explosives among other cargo before joining convoy HX-301, departing New York on July 25, 1944. The main body of the convoy reached Liverpool on August 8, although AMASA DELANO and many other ships were diverted late in the voyage to Oban, Scotland, probably arriving there about the same time the rest of the convoy reached Liverpool. In mid-September the ship made at least one voyage to France, carrying supplies to the Normandy beachhead.
AMASA DELANO departed Swansea, Wales, on September 19, 1944, and joined convoy ON-255 that departed Liverpool on September 22. The convoy arrived in New York on October 9, 1944.
If you want to obtain a photograph of AMASA DELANO, see http://www.usmm.org/photosource.html for sources of photographs of World War II-era merchant ships. Your best bet is Mr. Hultgren, since his collection focuses on Liberty ships; AMASA DELANO was a Liberty ship. I know enough about his collection to know that he apparently has an image of the ship. Mr. Hultgren is quite elderly but at last report he was still actively managing his collection. I understand he charges $10 for an 8x10 print.
Additionally I have found two online photographs of AMASA DELANO in her postwar configuration and under two of her postwar names:
As SS STRATHPORT: http://searcharchives.vancouver.ca/s-s-strathport-at-dock;rad and http://searcharchives.vancouver.ca/uploads/r/null/1/0/1022300/975da1c7-aab2-4cab-8017-18b9eda69770-A47629.jpg
As SS ELPIS: http://searcharchives.vancouver.ca/s-s-elpis-at-dock;rad and http://searcharchives.vancouver.ca/uploads/r/null/1/0/1007272/052a34a9-b353-455c-800c-7f67b8311121-A39756.jpg
Ron Carlson, Webmaster
Armed Guard / Merchant Marine website