4500 air tank

Hay fellow pcp air gunners, I have been offered a 1 liter bottle that was used for hpa paintball and the top valve is different than my 88cu ft tank and no gauge. So my question is what valve and gauge do I replace it with to make it a portable refill tank and how much and where do I get one. I want to connect my hose with quick release to it. Thanks for any information to help.