R.R.
The tubegun does not require any machining to the 700 action. That is not to say that you might require action blueprinting and perhaps drilling and tapping the action center screw. I'm not sure about the absolute necessity of the latter.
You would not be importing anything to Canada other than accessories to your 700 action.
Being a glue-in, there is no necessity for a recoil lug, although some of the prototypes made use of a 360 degree lug to hang AR type fiberglass forend tubes.
The prototype tubegun made use of a Remington 722 action. This rifle was in 22-250, and actually made its competitive debut at Cedar Springs, ON in 1999. Later protos were a LA 700, SA 700, and later the short Remington Model 7. Since the tubegun does not make use of a bolt stop, the Model 7 can easily be made to eject a fully loaded 6.5X.284. To my knowledge, neither the LA 700 or Model 7 kits are available from MAK.
You can see the clear (silver) anodized 722 proto in the photos on the MAK website. It was designed for prone and F-Class competition initially, but has found its way to across-the-course competition (with magazine), and the varmint hunting community.