I could get through a bench workout at those percentages. ZERO chance at getting through that many sets of pulls at those percentages. Full credit for gutting it out. I would have to go several levels down from where my numbers put me to have any shot at completing a Sheiko cycle.
You're a beast at benching so I have no doubt you can get through Sheiko bench. The pulling is brutal but the squatting has to be the worst in terms of gutting lifts out. The squats, sometimes twice in a workout, just make you wish the end is near lol. Having said that, I think you underestimate yourself in the pulling. I think you can handle it given you're not on the road driving for those crazy hours you sometimes do. Plus, while I'm not saying they're easy bc they're not, deadlifts off of boxes are much more forgiving than pulling off the floor so roughly half or slightly less of your pulling volume is from a box instead of the floor which allows the total pulling volume to be pretty high. Finally you're Masters Fucking Powers and you'd kill it lol. I did take 40lbs off my meet PR for this training cycle bc of the back issues.