Building the bottom end

[Ron1]

With a 331 or 347 stroker and the right combination heads, intake, carb and cam, there is no reason you could not reach your goal without the S/C. I would do some investigating and talk to the cam companies, talk to some of your local engine builders and see what they think.
You might contact Dave at www.jdsperformance.com and see what he says. Give them your 500 HP.
Do keep in mind that the 66 will need a lot of other work to keep that HP in check. Subframes, some sort of traction set-up like SSM or www.calvertracing.com
I drove my 65 coupe everywhere with just a 306 CI motor, fairly mild cam and a 150 shot of N2O. With the SSM lift bars, on an 8 inch slick it went 12.04 at 118. Of course the 8 inch rear exploded one weekend, the T5 got real loose, but it ran great.

Ron