16v Driveshaft outers - which ones to use?

Hey,
I've just fitted an ABF in my mk1. I've sourced the rocco 16v drivehshafts and i decided to fit brand new CVs all round, the 100mm inners were easy. But i'm not sure whether to use MK1 golf outer or the rooco 16v ones. I bought both types, and the 16v ones are much larger,

a; will they fit?
b; how will the different outer CVs affect the driveshafts' total length?

Please help.

Don't quote me on this, but I believe 100mm outer CVJs are 4mm longer than 90mm outer ones, once fitted etc.

i've just measured my shafts (without CVs) and they are 430mm and 650mm approx. The outer CVs are much longer for the rocco 16v.
Does anyone know if these are the correct shafts?

I'm still unsure whether to fit the smaller and shorter mk1 outer CVs, or the larger and longer 16v rocco outer CVs.
Lots of you have done this, please give me a clue.
Thank you.