Never heard of a 4 bolt main 327. 302, 350, & 400, yes.......and an obscure reference to a 305 Canadian truck engine once.

While there's certainly no harm in a 4 bolt main, this may be another of those "more is better" things. Keep in mind, most performance BB Chevs have two bolt mains. Although, getting real hp in the range stated is going to take quite a package. Modifying the stock 327 block shouldn't be too much of a problem. I think Milodon, and probably others, make 4 bolt caps for the 327, and a competent machine shop can do the modifications and install them.