The answer's the same as I posted on the mustang group.

Sorry if you dont like it..  but kudo's for figuring out where it should
have been posted, in the first place.
Paste:
I assume the rad fan is running and the condenser coil is clean. If not,
fix that first.

See if you can find a hobbyist with a set of full gauges to help you.
There being something wrong, the gauge you are using is only an indicator
not a tool.
 
The reading you  are getting with compressor on indicates either a bad
compressor or a damaged orifice tube (the little 'jet' that restricts
flow so as to produce cooling)  
IOW, that pressure is too high, indicating either not enough flow through
the compressor.. or too much through the orifice.  A hint as to which
would be the temperature of the vapor line at the compressor.  If it's
near ice cold, likely the orifice.  Likewise the line OUT of the
compressor to condenser being less than 'too hot to touch' would point to
bad compressor valves.

That last being too hot to touch, along with the pressure you're reading
would possibly indicate someone just 'dumped a can in' to see if it would
fix the problem.

The pressure you're seeing with compressor off means nothing, as
equalized pressure (no flow) relates to ambient temperature and is likely
twice '65' (look up a temp chart for 134a).  This is ALSO why you cant
tell if there's too much or too little refrigerant just by reading some
pressure without the system running.

Summary:  The gauge you're using assumes fully operational system with
the only variables being the switch-point of the low-pressure cutout and
the amount of refrigerant in system