The hole pattern for the G-Clip is based on the spacing of the small Tek-Lok. Both their holes are 1-inch center-to-center. Large Tek-Loks ate 1.5-inches center-to-center.
The Enuff sheath includes three "unlined" holes per side for attachment of the G-Clip. This allows the sheath to be carried either high-ride or low-ride and also provides additional versatility when configured for canted or horizontal carry. Although the 1-inch spacing of those holes does not support the use of large Tek-Loks, if you consider the unlined mounting holes AND the grommets that secure the two halves of the sheath together, there is some good news. The center-to-center distance from mounting hole to grommet is 1.5 inches and would technically work with a large Tek-Lok. Even though the internal diameter of the grommet (.178-inch) is smaller than the outside diameter of the Chicago screw post that accompanies Tek-Loks (.203-inch), you should still be able to make it work. Tek-Loks typically accept the Chicago screw posts and the 8-32 screw passes through the sheath. The outside diameter of the 8-32 screw is only .160-inch, so it fits through the grommet without a problem.
If you use one purpose-designed mounting hole and one grommeted hole, the Enuff sheath should fit a large Tek-Lok without modification to either.
I hope this helps.
Spyderco Special Projects Coordinator
Founder and Lead Instructor, Martial Blade Concepts