I need @ 600 hp and still remain na motor, is it possible ,or should I engine swap.

Ray @ raylar is the best 496 "doctor" with real world testing

He will give you + 600 N/A reliable HP's @ reasonable cost from your 496

Contact him @ http://www.raylarengine.com or for more info do some search on this forum "raylar"

You can get an honest 525hp still n/a with the Raylar kit...
Bob from Full Throttle built one and dyno'd it, and it was right there, as advertised...
It's a very nice looking setup, too...

I don't know about 600hp...
Kent

Just for another possible source, check with the folks over to Arizona Speed and Marine.

another thing that comes to mind is that when I read that some one dynoed an engine are we still talking about prop hp or flywheel hp. I'm hoping that maybe ARF heads ,exhaust ,cam and other mods could get me the 600 hp, but I haven't been able to find any threads that indicate someone has done it before.

Only heads for these 8.1L's that I know of are the factory ones and the Raylar's.

The Raylar's are top notch . Those involved with designing/producing these heads are Raylar / Profiler / Darrin Morgan from Reher Morrison.

Darrin has said that the OE heads are not good from a performance standpoint and that even though porting will make them better a different designed head altogother was needed and thus the Raylar head.

My 496 sucks... I only got 800hp.

did you achieve that naturally aspired,and if so how agressive are the mods?

Naturally aspired, didn't know there was such a thing...

As far as naturally aspirated, I didn't know there was such a thing either.

I should have looked at your avatar