Yes, the links to former posts and photos aren't working (yet? Gary?), so it's a bit of a pain. Reading the various posts and making sense of the thoughts are what makes working on Opels fun. There are LOTS of different opinions, and many are right. Different, but right.
I have a number of Webers right now waiting for re-builds and homes (as in running Opels (
) and only one has a vent bowl connection (a 32/36 DGAV with electric idle solenoid, so it must have been a California car). A new 38 DGAS I just bought had the casting hole for a bowl vent, so I drilled it out and tapped it for a barbed connection. Another (a 38 DPS 100, which looks to be a manual choke version of a 38 DGAS with an electric idle solenoid) has no place for a vent bowl connection. My other Webers (a 32 DFM and a 32/36 DFAV) don't have a bowl vent, nor the casting location for one.
The key thing is that NONE of them have a connection to VENT the cannister. The Solex comes with a hose nipple that connects internally to the carb throat, that allows cannister gas to be vented into the engine for combustion. So you need to install a fitting into the air filter assembly, downstream of the filter (so it's the lowest pressure possible, but NOT a vacuum) to connect the cannister vent to. For the top-mount pancake filter, the photo I posted in the referenced thread shows one way to do that. If you are using an adaptor to fit the stock GT filter snorkel, then you need another connection (besides the valve cover vent) to connect the cannister to.