I, and other respondents on this Community, are in general not Doctors. Some have considerable related professional experience, but all are responding as individuals/patients who are sharing what their experiences have provided them.
Not being a doctore, I do not know what "LGL" stands for, you may get some more input if your spell it out.
A total cholesterol reading over 300 is very troublesome, didn't your doctor prescribe a statin drug?