Be very carefull if you replace the switch. The number you gave is a replacement number for an early number that had its function changed in about 1981. Many suppliers just use the early switch and change the number.
The difference in the switches is that the new number you gave is a low/high pressure switch not just a low pressure switch. With R12 it wasn't as necessary but with a conversion it is very important that the compressor be shut off at the high pressure setting (somewhere between 3-400psi. If you have any refrigerant the switch should make contact untill pressures get high.
Bosch Master, ASE Master, L1
33 years MB technician