Standard springs size?

I am thinking about changing the shocks/springs all around and I was wondering what's the standard size for the front springs on a Mk2?

I've see all sorts of numbers so far:

347

346

348

343

307

310

344

315

The same goes for the rear ones... several sizes available.

Supposedly, the compression ratio matters too but I can't seem to find anything about what they are fitted with when new.

Edited 3 October, 20178 yr by Inex