Aluminium v cast iron cylinder head

[Austin in the Shed]

I think if you asked 10 owners you might get 3 different answers of which cylinder head they prefer.
CI, there's 3 choices Low comp.Late Ruby or sports 9E 1. Numerous Alloy heads to choose from.
I am not too sure on wedging early heads but it does raise the compression ratio.
There is always a trade off on compression ratio and gas flow transfer to the cylinders on a side valve.
One Seven owner I know dyno tested a modified late ruby against a Ricardo and saw a 3 BHP improvement with the alloy one.