2412 was a commonly used airfoil in many of the more succesful early RC birds of the 50's and 60's so you won't go too far wrong if you use it for your model. It has 1.92% camber compared to the Clark Y's 3.43%. Both are 12% or very close to it (11.7 for ClarkY). So the 2412 will be more capable if you start doing much inverted flying or general stunting. The ClarkY should have the advantage in lower landing speeds and ease of building. The 2412 having a curved lower shape will reguire some jigging of some form. But for a major building effort that comes with an 80 inch model this isn't much to deal with either way.

I got all this from Profili2 BTW. It's got both airfoils in the database. With it you can design your wing section and print templates complete with spars, sheeting and leading and trailing edges.

If you think you tend to build heavy then I'd suggest you choose the Selig 8035. It's a slightly thicker section designed for use on scale warbirds that often have higher than normal wing loadings. It's suppposed to have a very kindly stall charactaristic when built using a fully sheeted wing to retain an accurate shape.