I have 2 running slants without the OSAC valves. I think this was an emissions control device, at the expense of some power.
As for the PCV, I have noticed the condition you are describing. I have not yet determined the cause and I haven't encountered such an easy solution as simply using a different port.
I have been guessing that different timing causes vacuum settings to change and that depending on the year model carb, the port was tuned to have a correct vacuum signal. Yet another reason it is so difficult/important to properly combine all the elements.
I've yet to see a good explaination of how to fit all this stuff together properly from a big bin of unidentified parts. (Such has always been my luck) Trial and error has resulted in a pretty kicking street six at the moment.
