Have you seen the large (12"-15" blade) timber framing saws? They're just a heavy duty circular saw with large blades, seems to me. The Makita I recently saw was only 12 amps at that...
What would prevent someone from making their own from a decent circular saw to begin with, then fabricating a larger safety housing for the blade? That housing alone, it seems, jacks the price up about $200.
Just curious, H
ps: I'm not looking for dire warnings from scaredycats and hypersafetyites. If you have genuine experience with this sort of thing and can offer reasoned caveats, however, feel welcome to offer something.