I have normal 3-leg mike stand which is not stable under heavy rode NT-1A (almost 2LB)
so I am thinking about iron-cast round stand, will this work? (e.g. Athletic MIC-6E)
thanks

you probably will need to add more weight to the base.  

The cast iron base has a smaller footprint on the floor. It will also require more weight.... probably a lot more weight to keep it from tipping.... 

you can also add more weight to the "other end" of the boom to counter balance the mic's weight..... like the big construction crains do. 

I have used a fairly large C-clamp on the opposite end of the mic boom to balance things.  Sand bags are also great for stabilizing stands:  http://www.sandbagstore.com/lighting--grip--and-display-sandbags--saddle-sandbags.html?gclid=COHQ7e_ZirMCFWGnPAodoQMATQ