As for hardware specs.....
a Lisa heavily updated.... actually, scrap that.
GeForce8 with Lisa integrated, when going below 8bit colours, it switches from Chunky to oldschool Planar type display.
Soundblaster Live! with integrated Paula, the Paula module upgraded to handle 2.88 MB floppies at normal speed.
CPU would be dual AMD Athlon64 x2
the Kickstart should also include a hardware 680x0MC (full w/ MMUwhere applicable) emulation module, to run the oldschool crap we have with even less problems.
Blitter and Copper and such upgraded as neccessary to keep up with the speeds of the Lisa Geforce
1GB Chipmem, upgradeable to 4, and 1GB fastmem upgradeable to 16 (8GB for each CPU)
So.. down to less important junk:
DMA133 IDE, for upto 4 devices.
10/100/1000MB Lancard. (anyone who claims wireless is a goodiea is a liar :P)
6*USB 2.0 compliant ports. (New Amiga Mouse and Keyboard and joysticks are hereby going USB)
Parallell and serial ports, both your normal SVGA and the not-so-normal 23pin Video ports.
DVD burner, dual layer +/- RW
Opera or Firefox web-browser
That's all I can think of for now....