Do you need Flameking specific filler valves or will the standard valves that are common work ?
Define “standard valve”.
Whatever connecting/valve system that is used, the refillable tank must be upright, while the donor tank is upside down. Beyond that, it’s user preference.
I like the Flame King refill valve with it’s spring loaded trigger valve. Easy to open and self closing with one hand, while the other hand opens and closes the vent on the tank being refilled.