Well i think the standard set you're asking already exists. In the fear to say again the same thing, icons available on GameIcons are in 120x96, it became a standard as now most of ppl who makes icon for WHDLoad used this size.
Why not follow this standard.
I wish you good luck in this project and lot of pleasure for this new year
To RCK : if you're interested to add it to your download page, direct link from aminet for the 2nd pack (.readme include the content of the archive)