For 85_SS_302_Coupe, the carb is an edelbrock.
Like said, the white plugs are a lean condition. Did you just install the carb and not do any adjustments to it? You may have to move the accelerator pump linkage bar up to give you more fuel.
For your timing, it sounds like your initial is fine, but keep the timing light on it and rev it and see how much the timing increases. Most of your timing should be in by 3000rpm.
Use this link of the edelbrock carburetor owners manual, if you don't already have this, to do some basic tuning.
http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf
I hate to say this to, but I also have an 85GT, and as you know there are vacuum lines EVERYWHERE and I can almost guarentee something somewhere is leaking, but chasing the leaks is difficult. You can look for obvious signs of cracked or disconnected vacuum lines, and you can go through one by one taking off lines and plugging them to see if the car runs differently. To see if your vacuum advance is working, put a vacuum hose on the port of the vacuum advance and suck on it. If you suck constant air, it's bad, if you can't, it's good.