Can I put a 10 speed 11-36 cassette on a Road Bike with a 50/39/30 crank?
Most likely yes, the M772 will work.  As you have already calculated, the capacity is within spec, and the maximum sprocket size is out of range by just 2 teeth.  In my experience this is very likely to work, so long as the rear dropout on your frame is not especially near to the axle, and so long as you tighten the "B screw" more than normal with a smaller cassette.

Whatever you do, don't buy a "Dyna-Sys" model, because they aren't compatible with your shifters.  This rules out the M780.

Also note that with the super-low gear of 30x36, you do somewhat increase the chances of breaking a rear spoke (or the chain) if you put a large amount of force into the pedals with such low gearing.  This isn't a big concern, but don't get carried away with it unless your body weight is quite low.