Is it safe to mount a 65" TV to the wall using 1 and 1/2 inch lag bolts instead of 2 and 1/2 inch lag bolts?
I would cleat the mounting using horizontal 2x4s or some thicker plywood mounted on the surface of the wall. It's less sightly, but you can distribute the weight along more studs. I would not try to mount it across only 2 studs using 1.5" screws.