Take the long view.
A preserved Amiga will only continue to be rare, unique, and more treasured in the years ahead. A 500 with it's innards hacked out in exchange for a commodity board (obsolete sooner) will only be a disappointment in just a few years time.
Maybe you could keep all 3 and use them to their strengths. A500 for games and small apps. A2000 for great expansion. A3000 for 32 bit speed and VGA out.
Take a clue from Antiques Roadshow, when someone updates an old original and completely destroys its value to the future.
