http://zshop.net.au/280tech.htm
I'm not looking for an engineer to certify mods, I was just asking about wheel sizes....the engineer was in Taree and very helpful and easy to talk to. I decided to go very conservative with 15 X 6 panasports and 205 60 tyres.
A bit more info ...this scan, part of a comparison with a Celica, is from the same book as the last one " Datsun Z series - the complete story " by David G Styles and the link shows 6JJ X 14 as an option.
Not sure how "verifiable " they are but hope it helps.
Pete