What Levin has been talking about is NOT what is commonly known as a "Constitutional Convention" (with all of its attendant perils).
It is an Article V Convention.
What is a Convention of States? (General FAQs)
Convention of States Home Page has a great deal of information on the whole topic.
All constitutional conventions are Article V conventions, unless you're planning on tearing up the present Constitution and just starting over from scratch. Why? Because Article V is the only place where the rules for amending the Constitution are found.
And, with all due respect to Mr. Levin, when enough states call for a convention - which Congress must call - then that convention is a plenary convention at which any and all potential amendments to the Constitution can be proposed, and any such proposed amendment becomes part and parcel of the Constitution upon ratification by 3/4s of the state legislatures, or by conventions in 3/4s of the states - depending on which mode of ratification Congress chooses (it is free to choose either one).
Now, here's the fun part: other than the broad outlines for what's needed in order to have a convention, the Constitution doesn't provide
any rules - or even guidelines or wishful thinking - for how such a convention should be run - do Robert's Rules of Order apply? How are delegates to the convention chosen, and how many delegates does each state get? Is a proposed amendment adopted on a straight majority vote, a 2/3s vote, or a 3/4s vote (which would be consistent with the 3/4 requirements in Art. V itself)? Who gets to propose amendments, only the delegates, or anyone who can muster a certain number of signatures on a petition? What sort of participation will the general public be granted? Will the sessions operate in secret?
And that's before we even get to the most contentious issue - the amendments to be proposed themselves.
I understand the frustration, but I do not think we want a constitutional convention called by 3/4s of the states; that would be a disaster of epic proportions - it would make Noah's flood look like a gentle afternoon sprinkle.