Thanks Chris. I'll reach out on email.
The problem with the CB and SL frame is that they both have that "tube" running from the top of the frame down to bottom of the frame directly behind the engine. I've mocked the motor up with both and I just cant get the carbs on as they sit exactly in the same place as the down tube. That somehow needs to be cut out and replaced with something but its probably cheaper just buying a new frame.
My friend is building a CB350F and has a couple of those frames. They split with two tubes coming down the back so i'm going to borrow one and see if the twin will go in. I suspect not as I think its taller than the four and is shorter front to back.
The bizzare thing though is it drops directly into an RZ frame. You would think it was made for it, even the rear top engine mounts line up. It also drops in from the top like the Drixton so its easy to install. Tech may have something to say about that though