HI Roxburyeric,
I have done the same thing many times over the last 15 years here in rocky NH - I pull up the bigger surface rocks that I can with the BH then spread the loam sorta roughly to grade, then rototill (with a walk behind tiller) then rake / level this out and seed. If you tear up the grass before you spread the loam it will make a mess and lots of clumps to deal with. I find its better to work in new loam with existing soil after the rough grading is done with new soil, then level it out.
We reclaimed an acre + of forest over the last two years due to hurricanes and microbursts taking down trees - its mowable right now after about 100 yards of compost material from our local dump but far from a nice lawn, so got 60 yards of unscreened loam delivered last week for $300 that while the ground is frozen and planning to spread over the high/low spots tomorrow (0-3" over existing grass and boulders) then york raking in the spring and reseeeding. I just want to cover the subsurface ledge/rocks - you know the 3-5' variety that dont move...
The harley rake is a great tool, but if there are any rocks near the surface like we have in NE it will not work that well - it's best in my opinion to leave the sleeping rocks sleep.
Carl