Big Seafoam OOPS, 79 300TD

Ok, so my last car was a gas VW Jetta and when I got it, it had an incredibly dirty intake manifold. I did a few seafoam treatments through the vacuum lines and it worked miracles.

I just got a '79 300td (non-turbo) and there's been a lot of blow-by. The air filter and housing is full of dark oil, and the car smokes much more than it should.
My thought was that since I was dealing with a similar problem, I would turn to a similar solution. I sucked a half a can of seafoam through the thin vacuum line coming off of the thick one that leads to the brake booster.

Since the big cloud of smoke didn't come out afterwards I just started to look up Seafoam treatments on these vehicles and found all this scary stuff about hydro-lock. Yikes.

I've only driven about 1/2 mile since doing the treatment, but I'm supposed to be driving almost 300 miles tomorrow (hence the desire to clean out the intake before getting on the road).
SO! Did I fuck things up? What do I do to fix it?
Also, how can I clean out the intake manifold? Will seafoam in the fuel do the trick?

Thanks