Yeah, funny you should bring this up- I just bought a Ninja reg, that's a 4500 psi reg, with 3k psi output, and I'm pretty sure it doesn't have M18-1.5 threads, like the CF airgun tanks do... I have found an aluminium tank that's 450cc's that takes 5/8-18 UNF... which is both smaller, and not CF. It's also from aliexpress. I really should have checked the reg's threads before I bought it...
Who makes the tank you're looking to put a valve in? Reason I ask, typical US made PB tanks are 5/8-18UNF, not M18x1.5.The only M18x1.5 threaded valves I've seen are the Acecare... Ebay or Aliexpress.If a US made tank, the Jubilee valve, is the only non regulated PB tank valve I know of. They are not exactly cheap, but, are really good quality.