Blackjack - I ran into a similiar problem when I was using the Pentroofs on my 427 as well. I ended up ditching the S-Tube on the back and buying one of Gessford machines modified DOVE plates with a pcv assembly in it for $80. Done. Finished. End of story and everything works great. It simply plumbs into the vac port on the back of the carb. I know you went another direction but halfway through your post I lost patience and simply relplied. Best wishes!
My unit is definetly no more than two inches high. You can see it in the back with the black hose to the carb.
