[Seaman]

You could very well have non-matching fittings. Flared fittings can have two different tapers. Typical hydraulic JIC fittings have a 37 degree taper, where SAE fittings are 45 degree. AN, or ArmyNavy, fittings typically have both. The o ring fitting shouldn't leak with 3000psi on it, this is a typical hydraulic fitting. I would take the filter housing, hose assembly, and block adapter to a hydraulics shop and have them put a compatible system together for you. Just look for a Parker hose and fittings dealer. They will custom make the hose also, so you get exactly what you need.

Dave