Well, there is more info about this kind of stuff over at http://www.screamandfly.com , but the general concensus is:
The 260's run hard, and can be modified to 300+hp. SVS is available, as is the Brucato PCU for tuning. Standard 16amp charging system.
The 280's run harder, but have the 40 amp charging system with the big external alternator, and have a rev limiter built in at 7850 I believe.
The 300 Drag's make 300+hp stock, but won't live as long. They will turn up to 10,000rpm and above though, in stock form.