Most of what my company makes in Pipe (J476) and J512/13/14 adapters are good from 150 Psi to 9,000 Psi. if making this part from Hex stock, assume stainless, then I am sure it can withstand the 30 Psi of beer systems (max), even with a wall thickness of 0.030".
I think this will be a custom part. Money may go better else where. But good project none the less. That is what we home-brewers are about.