[Barry_R]

I can say with a very high degree of certainty based on many dyno runs that the average 445 cube stroked 390 on pump gas will get you between 475 and 500 horsepower and +-500TQ. This would be with a set of tweaked Eelbrock heads, a dual plane intake, a slightly lumpity flat tappet cam and a 750 Holley.

I've had several customers build their own and get them dyno'd with comparable results - no magic involved...

So I'd suspect that with more compression, worked over heads, and a really snotty cam that 570 mark is very attainable...