What is the backspacing of 16x8 GTA Wheels

[hotrod]

What is the backspacing of 16x8 GTA Wheels? I'm thinking of putting them on a 1972 Olds 442 but need to know what I have to do to make them work.

 

[blackmonte]

http://www.turbobuick.com/forums/general-turbo-buick-tech/200426-info-gta-wheels.html might help, had some good information here.