Dream Spec (although probably not commercially viable):
68030+68881 both at 50Mhz
2MB CHIP + 2MB FAST on the motherboard
Expansion's can increase fast ram and chipram
AAA Chipset supporting:
Planer modes up to 256 colours (like AGA)
Chunky mode support up to 65,000 colours (like graphics cards)
Pallete 16 million
Hardware support for games (eg sprites)
New Blitter chip
New sound chip - DSP with at least 10 voice output
Now imagine that in you A1200 desktop as standard!
Probably retail for about £699 however back in '92.