Top end of the motor is fine. You don't need bigger valves. And stock heads will flow more than enough. Just rebuild with eagle rods with JE/Aries pistons. That's most cost effective combo and it will take a alot of hp.
And this shall be the plague wherewith the Lord will smite all the people that have fought against the City, Their flesh shall consume away while they stand upon their feet, and their eyes shall consume away in their holes, and their tongue shall consume away in their mouth.