Why not just buy a set of proper ROMs and see if it works? Seems a bit excessive just to save a few bucks! At this point you need two 2.0x ROMs for the A500/2000, or 1 set for the A3000(T). Unless you have two 500/2000 ROMs you are going to have to buy two ROMs. There is a set of 2.04 for the 3000 on ebay for under $7.
