I usually see 70 psig with engine off and pressures equalized, but could be 90 psig on a hot day (we get much hotter than TN). You should still get cooling if 60 psig, and that is certainly enough to actuate the pressure switch and engage the clutch. Does your clutch engage? If not, I think all 1985 had the infamous KLIMA relay box, so search that. You could bypass that with a manual switch or a simple relay, but leave the pressure switch in the circuit (I think Rollguy sells a conversion now). When not moving, you need the electric radiator fan to come on or you won't get much cooling. The temp sensor on the filter/drier does that and often fails or gets erratic.

If you do start fooling with refrigerant, consider HC's like Duracool or Envirosafe. They work great and are common in Europe and Canada where R-134A is outlawed (coming to the U.S.).

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans