I found a few rather bad photos of a few of the ships on the www.armed-guard.org web site. If you haven't found these, let me know and I'll send them to you.
I also found additional references to the convoy that indicate my earlier comment about there being no loss of life was incorrect. My original comments were based on information in Hague's book on Convoys. A second source says the following regarding casualties:
Hybert = no loss
Massmar = 17 crew, 23 from SS Alamar, and 9 Armed Guard lost (the Massmar was carrying survivors of the Alamar, which was sunk earlier on May 27, 1942)
Exterminator = no loss
Heffron = 1 crew lost
John Randolph = 5 crew lost
The losses on the Massmar may be incorrect, as yet other sources say the 23 survivors of the Alamar survived the Massmar sinking. Frustrating part of these searches - too many conflicting stories!