The single charge port on a fridge compressor will be on the suction or low side of the system. You can both evacuate and recharge from that point. You don't need a discharge port.
If you can't find a drop in replacement for R12 then I suppose you could always drop R134a in and see how it goes. You've got nothing to lose.
Another alternative - You could always tip the fridge upside down or on its side and drain the mineral oil out of the service port, remove schrader valve first. Evacuate the system and then suck some synthetic refrigeration oil (same amount as what came out) back in under vacuum. Then vac out again and recharge with R134a.
If you can't find a drop in replacement for R12 then I suppose you could always drop R134a in and see how it goes. You've got nothing to lose.
Another alternative - You could always tip the fridge upside down or on its side and drain the mineral oil out of the service port, remove schrader valve first. Evacuate the system and then suck some synthetic refrigeration oil (same amount as what came out) back in under vacuum. Then vac out again and recharge with R134a.
