I agree with Bulldog. That old trail has places with loose sand over slick rock, so you can take a bad step and really bust your ass.
The first year that I ever went up, it was 1976. There was a pack station there. I didn't have any problem finding the old trail, because I simply followed my nose. There was a lot of animal "debris" then. Soon after that, the "new" trailhead sprang up. The new trail is more gradual and a lot safer, but only if the north fork of lone pine creek is reasonable. If you go up the old trail, it intersects just above the creek crossing.
The big rock is the biggest rock at the top end of the Whitney Portal loop.
