Thanks for the input Lifer...
I also reached out to VQ and got this reply:
Hi Greg ,
Sorry for late reply your email .
The correct CG for F-82 is 95-98mm .
I'm suggest you use 96mm . It is about 3,77 inch .
If you use electric motor , I think you need move all battery to the nose and need add some more weight at the nose .
Wish you have good flying . Best regards,
Vinh Quang
VQ Model Aircraft
So appears I am close to where I need to be... certainly don't have to come forward to 78mm...
Thanks again - should have a maiden flight in the next week or so.
Greg