the 8.5's were in all the g-bodys steve88 said except the 84' hurst Olds. The cost to set up depends on Your goals. Strange has spool/axle packages for around $650 with c-clip eleminators,I use Motive "performance" series gears with good results(not the street gears), they're a little under $200. The g-body rears are getting harder to find & You can use the 8.5's from the 73-76 gm cars, with custom control arms & the right back spaced wheel & moving the shock mounts. http://www.maliburacing.com/iceman
This is Rick Fisher in monnett area, He should be able to make the arms You need(although I've never used him, I've heard nothing but good about him). I have many passes in the 1.3's in the 60' with my 8.5 from a '73 car. once your 60's get in the 1.4's Your gonna need an anti roll bar installed, as the g-body's twist up pretty bad.