Richard, I've made brew in these and way over carbonated in them. They were hard as a rock cold. That's why they were the only vessel I could think to use. I'm going to keep this at 30psi for the next week and see if it holds...if it does then I think it's a good fit. I don't think I'd use it over 25psi anyway. I'll let you know how it works out.
Back to scavenging yeast from it...you think it would be worth while? The stems aren't food grade.... Can't see using food grade parts on a wheel!