[DaveC]

4. The Precision Port should be 1" longer than Lv when assembled.

The last part here is a general purpose fudge factor. It should be pretty close for most circumstances though. Do the modeling, and see what difference a 1/2" difference in port length makes. My experience is that there are usually unaccounted for losses between the model and the actual article, and that a little longer port helps to make up for those anyway.
As zero said, I doubt there will be any significant difference between the two.