The problem with mk1 panels is they are too deep and will hit your seats as the mk1 door is thinner without internal windows. Also the buckets are tall and you will bash your hand when winding the windows. The shape of the pocket won't line up with a mk3 onward door either.
The buckets wont be a problem, as i am having electric windows
How will the shape not match up i know that they will most likely be smaller?
Has anyone got the dimensions of the riley elf ones?
The shape of the doors is rounder at corners. You could probably make it work but expect the depth will be a problem. A bit of cutting and welding would get you there tho.