Well, all of them are cast, some cast aluminum, some cast iron and
some both. As far a production automobile engines are concerned,
I believe you are right. I suspect that there were prototypes, and
maybe other kinds of engines that predated the B21 but for sure, the
first commonly available Volvo car engine in the US that had an aluminum
head and OHC was indeed the B21. Note that the lower end of that engine
was very much like the 8-bolt B20.

Filled up 2 different cars at $0.949 yesterday but there is at least
one station (same brand) selling the same gas at $1.059, so it may be
on the way up again.
--
George Downs Bartlesville, Oklahoma