Wellworthy cylinder head 1960 model 50

If you're looking at the one on eBay then it appears, to my eye, to be one of the "iron skull" cylinder heads where the combustion chamber is cast iron and the rest of the head is cast around that iron skull.
Not really desirable IMHO. I think full aluminium is superior in many ways.
Here's a bit about Wellworthy that I found on-line (not fact checked) https://nfknowledge.org/contributio.../#map=10/-1.55/50.77/0/24:0:0.6|39:1:1|40:1:1

Cheers

I had a Wellworty aluminium barrel. It had cast iron cylinder liners which had bits at the top where the heas stufs scrwed in. It cracked through the stud holes. There was no way to fix it, so I screapped it.

Thanks for the information everyone David