On the intake manifold, just under the carb mounting surface, you should see a vacuum port that's about the same size as the vacuum port on the HEI distributor. Since I'm not familiar with your carb, that's where I would plug in. Set the timing at 8 or 9 degrees advanced without the vacuum hooked up to the distributor and then connect it up after you get the setting you want. I use a white paint marker to mark the timing mark before trying to set it. Makes the job a lot easier when you can see that stupid mark, to start with, when the engine is running.