He said close to 90hp at 9k rpm, which isnt completely unrealistic for a 600cc bike, assuming flow is good, though I'd guess we'd need to see higher than 9k RPM to see those figures. 150hp per litre is (relatively) easy for smaller engines.
That would put RWHP at about 70ish.
Would be a fun ride, for sure, even at 60-70 hp.