They have way less material than making a head yet worth the same.

Ideally you could incorporate it in the head design for yourself!

Could even be the best inlet for a rotary valve head as not having
any valve its main issue has always been slow flow down low.
Since they put such little strain on the crankshaft, poorly casted
weak cranked Holden engines were able to rev to 8,000rpm consistently.
If the sealing issue is solved using todays coatings and some water
injection to remove carbon deposits, a small capacity rotary valve
A series with A12 crank could rev to 16,000rpm.