If I am reading your post correctly, you don't have the instructions that came with the Weber.
On the side of the carb with the electric choke and fast idle screw, there are two small vacuum ports. Weber designates the left one as the "purge storage plug" and the right one as distributor advance. When I first did my conversion, I hooked the distributor vacuum hose to this designated port. It's been awhile and I don't remember exactly why, but I later experimented with hooking the distributor hose directly to a port on the intake manifold. As I recall, I didn't find a noticeable difference between the two. I do know that a lot of other things were going on with the '85 at the time and I never really got around to doing any kind of meaningful comparison before I got rid of it.
I am sure that someone on the board can explain the principles involved but thought I would get this to you in case you don't have the instructions.