The workshop manual says grease the speedo drive and the axle and thread with "multipurpose, medium fibre, lithium grease" The Shell product it lists is Shell Alvania R3.I clean parts with solvent or kerosene and an old toothbrush. It's a good idea to lightly lube the axle with any kind of lightweight oil to prevent surface rust. I've heard Simple Green is bad for aluminum.
Simple Green - I have not used any of their products but apparently there is now a product specifically for automotive which meets a Boeing material spec.
Quoting their web site "Extreme Simple Green Motorsports is ideal for use on aluminum, chrome, titanium and other high tech alloys, painted and gel-coated surfaces, anodized and electroplated parts, carbon fiber, a variety of metals, plastics, rubber and much more."
I am going to track some down to give it a go.
Whilst the front wheel is out, you may wish to carefully pick out the bearing seals, so they can be reused, wash out the bearings and repack with high temp bearing grease to prolong their life.