Jay,
I wasnt given advertised duration figures. TBH, I thought cam manufacturers were moving away from advertised duratio to sort of compare "apples to apples" as it were. But I could be wrong....I'd like to peak around 6000-6200 rpm and shift around 6500-6600. As for horsepower I think 550-580 is doable. Its such a light car I'm sure I'll scare the hell out of myself....
Can you look up the cam specs online and match up to the specs you have? DCR calculators require seat to seat duration numbers; if you plug in the .050" numbers to the spreadsheet I gave you, you'll get the wrong answer.
The 427 sideoiler dyno mule in my book made about 580 HP at 6400 RPM with the Webers and a Comp Cams 308R roller, which is 312 degrees seat to seat, 262@.050, and .674" lift. That was also a pretty sophisticated short block with a lot of low friction tricks that were probably worth at least 20 HP. That engine also had 10.5:1 compression, which was a notable compromise with that cam, because the short block had been put together for Engine Masters and 10.5:1 compression was mandated by the rules. DCR on this engine was only 7.1:1, so more compression would have picked up some power on this engine.
Bottom line on this is that if you are stuck at 10.5:1 compression, you will need a pretty big cam, like that Comp roller, to get to your horsepower target. I'd guess that to get to a reasonable DCR of 8:1 or so, you will end up with a much smaller cam, which may preclude reaching your horsepower target.
If possible, I'd consider going to a higher compression ratio, or going to more cubes. It is much, much easier to make the horsepower target you have in mind if you alter those two variables. Otherwise, you could revise your horsepower target down, because even a 500 HP 427 will yank that 2500 pound car around pretty well...