Additional discussion of this topic was covered in a post I made on 7-17-13. It was titled, "Update on 41 Rear Seal and PCV valve." I can post a picture of the valve I installed on my plugged draft tube if it would be helpful. I do think the time and energy I spent on trying to eliminate a rear seal leak by this method was a total waste of time. Here is what I said at one point in discussing this topic:
"As I understand it, when I talked with the shop foreman that did my rebuild, he stressed that the PCV system works only with the right size PCV valve and the correct mixture of vacuum to fresh air. If there is too much fresh air entering through the valve cover vents or an unplugged breather tube then the thing doesn't work.
I am suspicious about the postings of those who have adapted their cars/trucks to PCV venting. How did they do their engineering to establish the right vacuum/fresh air ratio. Plugging up the breather hole in the block, or the breather tube does eliminate the possibility of oil leaking from a breather tube but is it really recirculating crankcase gases back into your intake manifold?"
More dicussion on this topic is included in this link.
Update on 1941 rear seal and PCV valve Good luck, Mike