I don't think it is much of a debate at all. There are a bunch of guys saying they have 900 hp SB engines and they have track times and dyno sheets to back it up. There are one or two guys who say that they don't believe since they haven't seen it themselves. Seems to be that Monte's myth is busted, 900 hp SB engines do exist and have existed for many years.

How much they cost depends but it looks like $40K to $50K turnkey for new parts gets you in the neighborhood. Maybe less if you do some work yourself and have some used parts. Maybe more if you just write a check to a big name engine builder who sees you coming.