Any standard 1/8" NPT threaded gauge will work - although you may have some clearance issues with larger faced gauges. I'd stick with the micro gauge.
As for pressure range, the G3 operates at ~150 to 160 psi. I think a 0-300 psi gauge is sufficient. I think the next most narrower common gauge is a 0-160 - which is too close to the operating prerssure of the marker (and makes it VERY easy to blow the gauge if overpressurized).
Graphite Dangerous Power REV-I
– TechT bolt engine, REV-I & Disruptive barrel kits, Prophecy V2 w/ Empire feedgate, Crossfire SS 68/4500
Maroon and Polished Aluminum Dangerous Power Threshold
– 7th Element board, TechT bolt engine, magnet trigger kit, REV-I PMD, Sly Dual Carbon barrel kit, Prophecy V2, Crossfire SS 68/4500
Black and Silver Dangerous Power F8
– APE Rampage board, VS bolt, magnet trigger kit, F8 gauge, REDZ barrel kit, Halo B w/ Exalt feedgate, PMI 68/4500
Polished Aluminum and Red Dangerous Power F8
– Virtue board, VS bolt, magnet trigger kit, Halo B w/ Exalt feedgate, PMI 68/4500