Hot Water Heating System Pressure Too High

We bought this house recently and I am trying to correct some problems with the heating system due to poor maintenance. The house has a WMcL WGTO 4 boiler with a mono flow tee one pipe system in the basement. The first and second floor baseboard radiators are supplied from mono flow /regular tees on 1" copper pipe loop in the basement. The baseboard supply is either 1/2 or 3/4 inch copper based on the length of the baseboard in the various rooms. Think this is all pretty standard for a1955 home in CT. The pressure gauge indicated a pressure of 35psi which is much too high from what I know . I thought the pressure should be around 12-15 psi based on building height. The 2nd floor radiators are approx 17-18 ' above the boiler in the basement. I think I read where the system pressure could/should be be increased to aid in purging air from the mono flow system which is prone to getting air bound. The system is old style in that the pump is on the return side and there is an old style cast iron green Taco air scoop with automatic vent and there is an automatic air vent on the boiler itself . Any suggestions? Thanks