Vacuum hose goes to ?, Some mods have been done by a PO on my 75 2.0 Options

[porschefile2010]

Hi again. Help! I have noticed oil or oil condensate gathering at the front left of the engine on the tin and vacuum lines. Also the car isn't idling perfectly and the plugs are a bit black except for the electrode which looks the right colour. I also notice today a bit of smoke in off throttle situations coasting down hill, but not under power??
So I went hunting the forums and thought maybe the vacuum lines were loose or split.
The car appears to have had a new exhaust setup put in and I can't find any trace of a charcoal filter or emmissions pump or whatever they used to have so there have been changes.
But to the point.
There is a vacuum hose coming out of the tinware front left of the engine right next to #2 plug. In my car it is poked out through a small hole in the rear firewall??? and not plugged in to anything.
Can anyone tell me where this should go? I figured it might be meant to go to the charcoal filter but if that is removed where then.
It also looks like there used to be a vacuum line terminal at the narrow end of the air cleaner which had something screwed or bolted to it and this has been closed off?
One other mod has been the points taken out of the distributor and an electronic unit substituted if that has any bearing on it.
Thanks in advance.
Richard