APS XTP CO2 conversion to HPA

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Has anyone successfully converted an APS XTP pistol to HPA?
I am curious as to if it is best to find green gas magazines that fit and put a quick connect plug in the bottom to convert to HPA running on 90 psi from the micro regulator line,
OR
Use one way fill nipples fitted to a brass magazine plug to convert the CO2 magazines so they can be pressurised to 800 psi (CO2 bulb pressure) by connecting a HPA fill line to the high pressure regulator so they can be used without a line during games once pressurised from a HPA tank,
OR
Just use a HPA pistol to M4 mag conversion.