[Tx Firefighter]

Here's the skinny...

Your old blocks were what, 2 inches ?

Your options are to either build a new set of 2 inch blocks to replace those old junky ones and reuse your springs.

Or, you can have your shop de-arch the springs 2 inches and do away with the lowering blocks so the rearend sits directly onto the springs. This will need shorter u bolts of course.

Don't sweat the springs going into negative arch. It's very common really. Many custom cars run negative arch springs once lowered down. I've even paid big bucks for brand new street rod springs that were negative arch right out of the box.

The route you take is totally up to you. 6 on one hand, half dozen on the other kind of deal. You just need to talk to the spring guys about their opinion. For economy, you're way ahead to not dearch your springs and to re-use your old u-bolts. But, you'll have to go to the trouble of building new blocks. If you'd prefer to spend some coin, they will drop the springs for you and build shorter u bolts so it would be an easier (yet more expensive) job since you don't need to build any new blocks.