Yeah, calibration would be a pain. but there is a "test" mode withe the tach.
and with this led swap, you don't take the needles off. the whole front comes off and you work at it from the back, leaving the needles in place.
Tha Kraken: http://www.focusfanatics.com/forum/ford-focus-builds-general-showroom/285082-meet-kraken.html