Hello,
I own a Rejuvinator I and have had no problems with NTSC. I am running a 1 MB FAT Agnus. and Kickstart 3.1.
I did try using the System with a Kickstart 1.3 ROM and had no problems with games as long as the game recognised 1 MB of Chip RAM.
I dio wire 2 switches to the front panel beside the RAm expansion cover, a PAL/NTSCX Switch and a 512/1MB Switch.
The Rejuvinator replaces the Daughterboard inside the A1000. You may still want to do the Pal grounding fix though.
Cheers
Shaf