Moving from a 500 to a 1300, help?

Hello, last september i took the harley davidson riders edge msf course and rode a buell blast, (500cc) and completed the course. my grandpa has been a rider all his life and he just bought a Honda vtx 1300r i believe, or whichever comes with the windshield and saddlebags, and due to past and current leg injuries hes going to give it to me real soon.im kinda worried about riding it, or learning to ride on it since its a big jump from a 500 to a 1300 but then again it would be a real confidence booster to ride it lol. i havent seen it yet, so if someone could get the specs of a blast and the vtx 1300r that would be great. any help at all would be appreciated.Just to let you know i havent seen it yet because my grandpa lives an hour away from us, and he doesnt travel far distances on it because of his injuries, he has a disease that is like eating away his bones in his legs, along with both knees replaced and ankle surgery. he's getting a trike when he can afford it and me and him are going to ride around together :D waited all my life for that day its going to be amazing :)My bad, its a 1300t