Your question is confusing.
You want to put a pcv valve into the exhaust manifold???
What year engine?
Yes the draft tube should be sealed off with a properly functioning pcv system. What kind of pcv system do you have? Factory setup? Homemade setup?
Road draft tubes work perfectly fine, especially for the type of driving and care an antique car gets. Put it back to stock, change the oil at 1 year or 3k mi and don't worry about it. Your engine will outlive you.
Are you saying that when you turn out the idle screw until it doesn't contact the stop, the car stays at 1200rpm?
