Next step, reconfigure the old damper for the new set-up. This amounts to unbolting the top, and replacing the shim stack. The OEM damper has six shims on it, and David's shim stack seems to be intended as just a replacement of that stack rather than an adding-on-to.
This is just after sliding the new shim stack on the old damper. You can see the top of the damper (end of the threads) is a little chipped and deformed. It looks to me like this might have been overtorqued at some point? I should probably replace that unit the next time I change the oil on the shocks.
Now the two units are essentially the same.