reddishdsb,
The 346 heads are desecent heads for mild racing and great for street, they use the later port design and need to have hard seats installed. These heads will out flow the 906 heads and respond better to light modifications, too much porting to do on the 906 heads to get them to where they really need to be. Done well (porting) these heads can flow over 300 by a good bit @ .600 lift. The trick to do is to keep the intake valve size @ 2.08 and use the 1.81 on the exhaust side, this will help the torque and hp, the intake side only needs gasket matching and a bowl clean up with the guide narrowed, a good valve job and then you can go hunting those Big Chevys.
