Picture has been posted.
So...what maximum LPG is considered to be the best to give you the best control over reading pressure?
Yes, the boxed values represent the working pressures (minimum and maximums) of those particular regulator models.
I would say 200 PSI should be the maximum reading on the low pressure gauge (not the maximum delivery pressure of the regulator). Anything higher, and it will become difficult to see how much you are increasing/decreasing the working pressure by.