There are only two bridges between NY and VT, across Lake Champlain (but also several ferry routes). The "Rouses Point Bridge" is just below Canada. I believe it is numbered as US 2.
The more southern bridge is between Crown Point NY and Chimney Pt VT (near Port Henry NY on the map). This one is just a couple of years old. Both routes are suitable for big rigs, and both are used by truckers.
VT Route 4, between Rutland and Killington is also a major truck route, so should be OK for your big rig. Sorry, I don't have grade info.
-- John V in Port Henry