Howdy trooper. I personally do not know of any kits that come with the Honda. Another option if you can not find one is buy the GB and mount from 49cc Mounting Kit Only - $219.99
and the Honda engine from Small Engine Warehouse: GXH50QHA - Honda Engine 2 5hp Horizontal 5 8 x 1 1 4 Shaft Muffler no tank
Great price for a GX50.
I have just finished building one (Honda GX50 with Grubee GB) and really, really like it. Smooth and nice. Well worth it's price and then some.
I would suggest going with the 50 over the 35 for what you are planing. If you do find a kit with the Honda, could you post it?
Edit; I have never seen a cannondale cad 2 hardtail, so I goggled it. I did not find your exact bike but most seem to have the rider leaning down and forward. You might consider new handle bars that allow you to sit more up right if your bike is like this. Is just more comfortable with not having to do all the work due to your engine.
Best of luck