Don’t fall for flow numbers as the best way to select a head as PRH said. There isn’t a snowballs chance in hell the big mouth head will out horsepower a W2. Ever.
BTW, the issue with the W5 head is Chrysler left the intake port incredibly small (the exhaust port is on the edge of being too big), the chamber sucks and the moron who decided to cut the valve spring pockets so damn deep should be publically flogged and never allowed to design anything but toasters again.
With some work they make good power. If I ever had the chance to do another set, I’d weld up the spring pockets, replace the seats and guides, squeeze a 2.125 in there with a 1.500 exhaust valve and use a 55 degree valve job.
Then you have to fix the chamber. Luckily, you can do it without welding.
