I'm replacing hardwood flooring but the subfloor isn't flat. In the area above this picture, I can slide two fingers under a 6 foot framing level that's laying perpendicular to the joists. That spot, where the sag is the worst (circled in red). To level the floor, I'm anticipating buying a temporary screwjack to raise the offending joist about a half to 3/4 of an inch, then sistering it across the entire span, then removing the screwjack. As you can see the staggered blocking (yellow arrow) interferes along the span, and there is another block on the opposite side. Can I simply remove these blockings?
I'm also interested in alternative ideas for fixing the sag. I've read of shimming with roofing shingles but that strikes me as adding quite a lot of weight.