How much can you lift?
To all those who have bad backs (myself included).
Have you considered doing sumo deadlifts? It shifts the burden of the movement from the back and hamstrings to the quadriceps and adductor/abductors, and can make it especially easier for dudes with TRex arms. It will still work on your back, but not as much as a conventional style. Many powerlifters, almost all of them in lower weight classes, deadlift sumo. However, the really big guys like Andy Bolton pull conventional.
I'm actually afraid to test a 1rm for a squat, since if my spotter is bad I could get seriously screwed over. Whereas, if I fail a deadlift I just drop the bar.