Both legal. 6.5x6.5 Is too. Depending on who you ask a 330 is legal in any watercourse/way set. They need some clarification in the book on this. I caught my bobcat in a 160 in a culvert this year and called the PGC to make sure it was a legal set before I made it (I had the cat and mink running it) and was told it was 100% legal. But then was told by some people on here it was not legal, even though I had called first to make sure it was. If you ever have any question your best bet is to call the regional office, or email the PGC, and after you get the answer get the name of who gave it to you, or save the email. The book is very vague regarding conibar use.
Call the office ten times and you'll get 10 different answers. Ask for a name, and sometimes they refuse to give it. Here's where you're lucky though, I've not been checked or run into any trouble through the years, but when I have been checked I found that most officers knew very little about the trapping laws. I don't set in any waterways cause I don't need to catch any dogs or cats. The way I define a waterway is,,, don't set above the high water mark. If you do the common sense things, you'll never have a problem. Most officers of the law can see what your intent is, and if it's clean,,,,, ur clean.
The better WCOs will observe your intent over the exact letter of the law. None will give you the green light to bend, shall we say, the law but if you correct, amend or pull your set there is usually no citation issued.
Beaver trappers traditionally had problems along the lines of distance between sets and dams and/or lodges.
I really like emailing them anymore. They always sign their initials on the email, and I almost always have my phone with me and can just pull up the email to show a WCO if I ever needed as long as there is service. Ususually get a response within two days.