Hi kenbker
I used to sail on a 1/4 tonner in Brisbane when I was a kid called Onehunga Bus and it was a straight bolt-on keel, so perhaps Whiting's 1/2 ton designs were the same set-up?
Penny Whiting (his daughter I think??) is still very active in the sailing scene over in Auckland. Some Googling may be able to put you into contact with her.
Cheers
Trace