It would be better for you to sell your Amiga 1200 Tower and buy yourself an Amiga 4000 or 2500
Keep your a1200 and get a ppc card for it and blizard vision graphics card an a4000 would cost a lot more to upgrade and ppc cards are a lot harder and more expensive as for th a2500 there a waste of space as there to old for modern software as the can not use aga .I have an a3000 and an 060 4000 and there both no way near my ppc amiga tower . :-)
I would not pay above 20 pound for an a2000 the one i had only cost me 3 pound .