Rockefeller wins in both New York and Pennsylvania and does much better, compaired to Nixon, in New England by picking up Connecticut and Maine. His support is somewhat diminished in the south, except for Florida, where I think Wallace actually does better. As for LBJ, his approval rating was below 45% in 1968 and with his declining health, I simply can not see him running an effective campaign. He keeps Texas simply because John Tower doesn't add too much to the Rockefeller campaign except for a fresh face - he was only 43.
In the end, Johnson goes down in defeat by a bigger margin than the actual 1968 election.
Rockefeller/Tower: 343 EV, 45% PV
Johnson/Humphrey: 124 EV, 40% PV
Wallace/LeMay: 71 EV, 15% PV