Power steering pressure hose ???

[6T7 C10]

Hello everyone. I have a question that I have not found an answer on. I have a 67 C10 that I am building and I installed a 68+ power steering gear box and I have a serpentine belt system from GMPP that is based on 90-95 models. The gearbox hose is SAE 5/8 male inverted flare and the pump is metric 18mm male o-ring. I got one of those adapters and it always leaks and I have not even started the truck yet. I did read you could swap outlet fittings on the pump but I do not have an old pump and did not see a fitting available online. I am about to buy a pressure hose for each system and take it to a place and have them spice the two good ends together to make one hose. I already stopped by my local NAPA and while they do hydraulic hoses they will not touch a steering hose. Anyone else tackle this issue with good results?