69 camaro/firebird rear back spacing?

[jlwdvm]

Trying to get a set of Vinatage Wheel Works V40's ordered for my 69 firebird TA track car clone. Looks like 18x9.5 with 6" back spacing is going to be a safe bet for the front with 275 Toyo R888s and Ride Tech Tru Turn (may have to use a spacer to get it dialed in exactly) and I will be using 18x11 for my 315 Toyo R888s for the rear. The car is mini tubbed and I am wondering what back spacing I should get for the rear. I will be using a Ride Tech 4-link for the rear mounted from the leaf spring perches on the rear so I can't narrow the rear too much. I will probably be ordering a Currie 9". I don't want too much dish on the rears either. Any ideas for the rear back spacing? I'm gonna order the rear end after I get final measurements with the wheel-tire combo under the car.