your higher rep range max is mostly determined by your 1rm, that's why there are all kinds of calculators that do just this. but as i said, there is variation due to fiber type. if you want to bench 315x10 and you bench 225x1, you don't do sets of 170x10 to get to 315x10... i hope that's obvious. same holds for 225x10. you're gonna have to focus on getting your 1rm way up and then you can work on rep work (again, how many reps you can do is mostly a function of your 1rm)
you want to focus completely on increasing your 1rm though that doesn't mean you just do 1 rep maxes. follow a program that focuses on increasing limit strength: 531, sheiko etc. a 5rm correlates extremely high to 1rm but you're right above that (e.g. 10rm) you're gonna have to develop strength endurance some. 12 weeks is plenty to do this if you have the raw strength.
again this is well established. do what you want though.