Sounds like you're almost there. I like a nice custom exhaust, it can really change the presence of a car if it's not obnoxious. I wouldn't be surprised if the vac servo on the distributor wasn't working. I struggled to find a working used one... I might still have a go at deleting the vac advance when I do my carb swap by using a distributor off a 4G64 and see how it goes.