This is a mode that actually came out in the very early days of the game browser, I have had the original values used for the mode laying around in my presets since those early days.
The biggest thing to note is that original mercy paintball was created when mercy had her old ult (mass rez) and was one of the best parts of the mode. Getting a full team rez and flipping the tides was one of the best parts about playing the mode.
This uses the original values for the game mode allong with giving mercy the old mass resurrection ultimate back. This includes the 15m rez range, the guardiaan angel reset when ulting, and a 2.25s invulnerability for her and anyone she rezzes.