1984 Ford F250 Diesel R12 to R134a

[Ducatidyer]

Been reading everything I can find on the subject and keep getting conflicting information. My AC system has no R12 remaining, blown compressor seal. I will be replacing the dryer, compressor, new or rebuilt, and all the hoses when I can find them. I will flush the evaporator. I will blow the evap clear with air and will vacuum the entire system down with an HVAC vacuum pump.
1, Should I go to a red orifice tube from the Blue original?
2, Should I go to a 1994 or later condenser, parallel flow type?
3, If I use the later condenser will the original type replacement hoses connect?
4, How much PAG 46 oil should I add to a new system if using the 1994 condenser?
I will weigh the added R134a to 80% of the R12 charge. Please excuse all the questions just looking for some clear guidance.
Thank you for any recommendations.