I would go for the 500mg stack, at 2g of test the sides start growing faster than you do, I dont think its THAT uncommon and using arimidex I guess would be your best bet, I dont think it will "solidify" your gains but you will gain less water so you shouldnt lose as much.
Why not up your stack to 0.75/1g of test if youre looking to do big test dosages?
UglyASS