Propane Tank

I recently purchased a refurb 500 propane tank to replace the one being "leased" by the local rip-off propane company. The tank did not come with a high pressure regulator and neither the big box stores or chain hardware stock this kind of regulator and are clueless. The regulator on the old tank was a Fisher Control R300 but I am unable to determine PSI pressure that it puts out (looked it up online). I am told that the amount of output is gauged by the usage in the house. I have a heat pump with a 75,000 BTU back-up propane furnace. I also have two 5,000 BTU propane wall heaters and a 28,000 BTU ventless propane wall mounted heater. The two small heaters are used very little and the large one is used for short periods of time. The water heater and stove are both electric. The run distance from the propane tank is 150 ft. of half inch ID copper line to the low pressure regulator. With this information provided, is there anybody out there who can provide me with an opinion as to what PSI output the regulator should be.. I've also seen adjustable regulators that can vary the PSI output as needed (I assume).. I'll take any help I can get at this point...

Propane Tank