Piecing together an A/C system

Posted this on FBBO before but didn't get any answers besides get a kit from Vintage Air but this is not what I want for two reasons:

a) cost - I live in Europe an shipping, taxes, customs add 8 to 900 dollars on top so I'll try to source parts locally.

b) I want to be able to get replacement parts locally.

I want to add A/C again to my factory air car (was removed by a previous owner) and have some questions:

I plan on building a custom setup and the only parts I already have is the original A/C heater box and a NIB SD7H15 genuine Sanden compressor. So I still need a condenser and I know that I should use the largest I can fit.

What size is the radiator opening on a 26" radiator car (car is in storage and can't measure myself)?

Is a parallel flow still the best condenser type to use?

The ports on the compressor are 7/8 threads - how critical is it to match that to the fittings, hard lines etc? Most condensers have smaller ports. Or should I try to get everything the same size (is a smaller port/fitting an unwanted restriction?)?
Some OEMs have condenser outlets as small as 5/16..

What about condensers with integrated dryers? Any advantage on having a separate dryer?

Thermal expansion valve (TXV): any suggestions for that part? Vintage air has electronic valves iirc - can these be fitted to a custom setup easily as I read that they are superior over TXV...

I might have to use an R134a replacement refrigerant - which non flammable would you use? R513a?


Thanks