[Franz]

4 to 1 ratio of oxygen to acet. Basic physics requires the 4 to 1 ratio for combustion.
Set your Acet @5 and your Oxygen @20 and see how it flys. If that doesn't support the tip, jack both up and maintain the ratio.
There are 2 valves on the torch handle that do all of the flame adjustment you'll need as long as the regulators are in the ballpark. My regulators are set @ 10 and 40 for the last 40 years, and don't get adjusted.
New guys tend to get way too absorbed in settings, be it regulators or amps & volts on a machine.
Your gague is fine, it doesn't need to be a 50# max, and I doubt the regulator will supply 200psi.