If Tony makes the track too hooked up, cars will not stay on the track. Or he needs to build higher fences..... Thunder Dome? Tony is shooting for a balance between super hooked up and a potato...
OP: I wonder if those springs were for a really hooked up track or a high banked track? Pavement? Maybe someone just put those springs on the car to hold it up and hoarded the secret sauce.
You want to be smooth and not upset the chassis. Keep it leaned over on the right side, make a big circle out of the track if you can. You will need to adjust your line from that to accommodate...
I would not order a shaft without measuring, risky. Plus you might be inclined to try a shaft you have that is not the right length, and break the new trans or drop the new shaft.
Nova lowers will fit with a spacer at the frame mount and relocating the jackscrew nut (my car has a second jack screw nut installed). The Nova lower moves the spring outwards closer to the wheel,...