There seems to be no middle ground with military retirees - they either get rid of everything or they preserve it with more care than they ever did while on active duty. Either way, the surviving family very often winds up with a lot of it.
If you haven't already, contact his kids. You might be amazed at the information they have. It's worth a try.
You might also contact Pearl Harbor Attack Veterans and Pearl Harbor Survivors Association. You'll find their addresses at Message #3422. Go back to the Main Page, enter "3422" in the box in the upper right corner labeled "Jump to #_____" then click on "Go". At the very least, they may be able to inform you as to the ship he was assigned to at the time of the attack.
If the above fails, contact me and I'll give you a couple more possibilities.