Guys... the 'classic Amiga' is now dead. It's official.
Hey, no squashing peoples' dreams, here! ;-)
Still, do you really want a machine based on the same hardware, or just a system that looks like the original Amiga? OS4 looks enough like OS3 for my tastes (or rather, a bit too much).
If you want a machine that will run old Amiga software without emulation, you're asking for trouble. Even if you de-solder some original chips from a real Amiga and build a new motherboard, getting compatibility will be a real pain. Note the number of Amiga apps and games that don't even run on real Amigas without several reboots. :-)