Buy a Scat 496 rotating assembly . All you have to do then is make 1 hp/cu inch, a piece of cake.
Use a hydraulic roller cam about 220/230 @.050" with about .550" lift. You can use the factory long-slot rocker arms and keep the stock valve covers.
Look for oval port heads with a casting # ending in 781 or 049. Have these rebuilt or better yet buy new edelbrock heads.
Compression should be ~9.5-1 for cast iron and 10-1 for aluminum.
You will have a nice idle and tons of torque. Shift at 5500 to 5800 rpm and have fun without breaking parts.