I love the 1st gen sleeper build! I don't think you will have to do hi-steer with that setup if you don't want to. I kind of have a similar setup on my '80 and I am maxing out 11" stroke shocks on stock steering. I just had to remove the torque rod. Lift is like 2" on some re-worked rears up front. It rides great too. I did add a huge beefy tie rod from a crossover steering setup but I never added the crossover steering because it's working so well as is.
OME springs are great to use, you'll love them!