Lost41b, I am the HLR's Lotus 41 registrar, VulcanGrey posted pics of my car above in the thread. 61 of the type 41s were built and quite a few of them passed thru California at one time or other, including mine.
It's going to be pretty difficult to narrow down which car was your grandfather's as, by the early 1980's the original color was certain to have been changed, so I can't go by that alone.
If you have more details that you can share with me, I'll do my best to track down the car. You can contact me off-list at tacogc (at) yahoo (dot) com.