Hi there! I'm here about the gas mask voices rather than the voice acting. You mentioned wanting someone good with audio editing for the Combine-style guards, and that's my day job.
I'm an audio engineer and sound designer for motion picture with six years of experience. I have decent experience on dialogue editing in cases of audio recorded during shooting and also ADR, and I currently work on atmosphere design for TV series.
I'm trying to get into game audio, so I'm not looking for payment. I want real project experience. All I'd ask is a credit and permission to show the work publicly.
I would be happy to work on this project as an audio editor and/or a sound designer. If it's useful, send me one guard line and I'll return a treated pass so you can hear where the gas mask sound could go.
You can reach me through here or Discord: gunkutadali
No game audio reel yet, but my film and TV credits are here if useful:
IMDb: https://www.imdb.com/name/nm13219708/
LinkedIn: https://www.linkedin.com/in/gunkutadali