Why go to R134, use HR12 insrtead, the A/C works to full capacity and there is no need to change any parts and nothing deteriorates differently because of the gas.
The only disadvantage is that you will have around 360grams of flammable gas in your A/C.

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Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.