Thanks for the opinions everyone.
Since the heads are said to flow 20% more than vortec's and their crate motor with less cam and less compression is advertised to make 420 (obviously that's crank, but false advertising is illegal... So you decided), and I know advertised not real world. But still, I would venture to guess it's more than 425 horsepower.
I forgot to mention it's got 1.6:1 Comp roller rockers, and I'm not sure because like I said I haven't had the motor apart, but it's supposed to have a roller cam and lifters. It's also supposed to have a forged 4130 Eagle crank. How do I verify what the crank is? Since I've got the motor out, It will be easy to check.
In all honesty, I don't see where 500lbs could be removed without a TON of money being spent. There's nothing in the trunk, no spare or jack, no carpet or padding. There's nothing but essentials in the interior, carpet, stock seats manual everything nothing power, basic stereo nothing fancy. Under the hood pretty much everything is aluminum that can be aluminum. I guess I could put a manual steering box and save 10 or 15 lbs and lose some parasitic drag from the power steering pump which is probably worth a couple HP/TQ and get an aluminum water pump (which is planned) and lose another 10 lbs. The car has a stock GM starter on it that weighs a ton, but it's going back on until I need a starter and I'll replace it with a mini starter probably worth 5lbs? Other than going to fiberglass body panels, I don't see what could be removed to lose weight. I see maybe 100 lbs weight loss being simple, before it gets down to light weight seats and a stripped interior with fiberglass panels and lexan glass. I'd be down with the lexan glass but that stuff is expensive and not DOT legal, and I want to keep the full interior. I'd consider removing the rear seats... They're such a tight fit that I doubt anyone but a small child could sit back there comfortably anyway.
I already thought about the carb being a bit big, but I looked at the Holley website and they have a chart for power level, max RPM, and cubic inches... And the carb I have is in the high end range of what they recommend.