Stainless spokes, the zinc plated ones are a bit crap these days and soon discolour and corrode. I would go for D.I.D rims they were the original fitting. My bike has the original rims and I am surprised at how good they are after 49 years, unfortunately PO or someone has rebuilt wheels with plated spokes which are already showing signs of corrosion. I have always been dubious about doing my own wheels, as your life does depend on them, maybe lace the wheels then get someone that knows what they are doing to true and tension the them.
I built a front wheel for my push bike when I was about 12, it seems I over tensioned it, I hit a big bump and the rim just went into a massive buckle resulting in me going over the handle bars. Memory of the cuts and gravel rash sort of put me off wheel building for ever 😂